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A LABORATORY 

FOR 

GENERAL 

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COND EDITION 



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A LABORATORY GUIDE 

FOR 

GENERAL BOTANY 
GAGER 



BY THE SAME ALT:-;?. 



FUNDAMENTALS 

OF 

BOTANY 

izmo^ ziz 4-640 Pages, 437 Ilfat5txatiaii& fleadUe 
Ootii, Round Comars. $1.50 Postpaid. 

P. BL-AXISTON"S SOX & CO., PHTT. \DELPHL\ 



A LABORATORY GUIDE 

FOR 

GENERAL BOTANY 



BY 

C. STUART GAGER 

DIRECTOR OF THE BROOKLYN BOTANIC GARDEN 



Second Edition 



PHILADELPHIA 

P. BLAKISTON'S SON & CO 

1012 WALNUT STREET. 






Copyright, 19 19, by P. Blakiston's Son & Co. 



FED 20 lb: 9 A-\ 



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THE MAriiE PRESS YORK PA 



'CI.A5M620 



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PREFACE TO SECOND EDITION 



At the suggestion of teachers who have been using the 
first edition, laboratory directions are added for the study 
of three additional forms, viz.: Exoascus deformans^ 
Microsphcera Alni, and UsHlago ZecB. The author is 
indebted to Dr. E. W. Olive for the preparation of these 
directions, and for a careful re-reading of the entire text, 
resulting in the correction of various typographical errors 
and other inaccuracies. 

The directions under the caption, VII, The Path of 
Water in the Plant (B-F, pp. 35-41), have been con- 
siderably extended at the suggestion of Prof. Ernest 
Shaw Reynolds, who generously consented to prepare the 
manuscript for the study of stem structure. Grateful 
acknowledgment is also made to Prof. James S. Compton 
for suggesting and preparing the manuscript for the study 
of bacteria (pp. 145-148). 

The author will welcome constructive criticisms from 

those who are using the book. 

C. Stuart Gager. 
Brooklyn Botanic Garden, 



VIU PREFACE TO FIRST EDITION 

The order of topics follows that in the author's Funda- 
mentals of Botany, but with only minor changes the 
Guide may be adapted for use with any text. 

The author is indebted to Dr. E. W. Olive for his careful 

reading of portions of the page proof. 

C. Stuart Gager. 
Brooklyn Botanic Garden, 



CONTENTS 



Page 

To the Student i 

PART I 

ANATOMY AND PHYSIOLOGY 

Meaning of the Terms 9 

A Generalized Plant {Spirogyra) ii 

A Specialized Plant (e.g., The Bean Seedling) i6 

Structure of the Foliage Leaf 17 

Transpiration 22 

Absorption of Water by Plants 29 

The Path of Water in the Plant : Structure of Stems 34 

Mechanical Uses of Water in the Plant 42 

Nutrition 45 

The Occurrence of Carbohydrates in Plants 46 

Formation of Carbohydrates 51 

The Digestion of Starch: Translocation 54 

Alcoholic Fermentation 56 

Respiration 59 

The Influence of External Conditions on the Plant ..;.... 62 



PART II 

MORPHOLOGY AND LIFE HISTORY 

Meaning of the Terms 65 

An Outline of the Classification of Plants 67 

Directions for Study 69 

Pol)^odium vulgare (Common polypody) 69 

Polytrichum commune (Common hair-cap moss) 80 

Marchantia polymorpha (A liverwort) 90 

ix 



CONTENTS 

Page 

Fucus vesiculosus (Bladder wrack) 102 

Vaucheria sessilis (Green felt) 108 

Spirogyra (Pond scum, Green silk) 112 

Pleurococcus vulgaris (Green slime) 116 

Bacteria 119 

Phycomyces nitens (or Rhizopus nigricans) 123 

Saprolegnia (Water mold) 127 

Albugo Candida (Blister blight) 131 

Exoascus deformans (Peach leaf-curl) 135 

Microsphaera Alni (Lilac mildew) 136 

Ustilago Ze£e (Corn smut) 138 

Agaricus campestris (Meadow mushroom) 140 

Puccinia graminis (Wheat rust) 145 

Isoetes (Quillwort) 149 

Equisetum (Horsetail) 155 

Lycopodium (Club-moss) 159 

SelagineUa (Little club-moss) 162 

Zamia floridana (A cycad) 168 

Pinus laricio (Austrian pine) 176 

Trillium (Wake-robin) 192 



A LABORATORY GUIDE FOR 
GENERAL BOTANY 



TO THE STUDENT 

THE NATURE AND PURPOSE OF LABORATORY WORK 

A . The Laboratory: 

1 . The word laboratory is derived from the Latin word 
labor, meaning work. A laboratory, therefore, is a 
workshop. The essential part of laboratory work, 
however, is not the manual but the intellectual. 
Handling specimens, manipulating apparatus, tak- 
ing notes, and making drawings, all are essential, 
but are wholly secondary to thinking. A laboratory 
exercise should be regarded always and primarily as 
a thought exercise. Everything else that you do 
with a specimen shoud be secondary to thinking 
about it, and done only to aid thought. 

2. The aim of laboratory work is to obtain facts at first 
hand. Reading books on plants is only studying 
about botany. To study botany one must have the 
actual plants before him. It was Louis Agassiz 
who said, ''If you study nature in books when you 
go out of doors you cannot find her." The posses- 
sion of this first-hand knowledge makes the reading 
of botanical books not only more easy, but vastly 
more interesting. You can take more away from 
the text because you bring more to it. 

3. Another aim of laboratory work, not less important 



2 A LABORATORY GUIDE FOR GENERAL BOTANY 

than the one just mentioned, is to acquire scientific 
habits of thought and work; to learn the method by 
which knowledge of the given science is acquired. 
The scientific method differs from the unscientific 
in laying emphasis upon the absolute necessity of 
an orderly procedure in thinking and doing, upon 
willingness to put aside prejudice and preconceived 
notions, upon scrupulous neatness, accuracy of 
thought and work, and careful attention to minute 
details. The scientific method is not peculiar to 
the natural sciences : it is just as essential in history 
or language-study as elsewhere, and the highest 
success in any intellectual pursuit is not possible 
if the requirements of the scientific method are dis- 
regarded. 
B. Observation: 

4. Observation is not merely looking at a thing. It 
means looking for a purpose. The mental attitude 
of the true observer is that of a questioner. The 
great Swiss botanist, de CandoUe, said, "The in- 
terrogation point is the key to all the sciences." 
Observation, then, consists in asking as definite 
questions as possible about natural objects, and 
seeking their answer, not from the instructor or 
the text-book, but from the object itself. 

5. Remember that your specimen is the final authority 
in all matters of fact. Your first question should 
never be, *'What ought I to see?'' "How many 
parts ought the specimen to have?" but always, 
without exception, ' ' What Jo I see ? " " How many 
parts does the specimen have?" Possibly your 
specimen may be found to differ from that of your 
neighbor, or from the descriptions in the books. 
If so, record that fact, and endeavor to ascertain 



TO THE STUDENT Z 

whether your specimen is abnormal, or whether 
your observation of it is at fault in any way. 
Always try to see all you can with the unaided eye 
before resorting to the aid of a hand lens or microscope. 
C. Experimentation: 

6. In mere observation one takes conditions as he finds 
them; in experimentation, he determines, within 
limits, the conditions under which the observation 
is made. It is never possible to control, absolutely, 
all the conditions in any experiment, but this is 
partly compensated for by arranging side by side of 
the experiment proper, a check or control. In the 
experiment and control all conditions should be as 
nearly alike as possible save one. The golden rule 
in experimenting is: vary only one condition at a 
time. Then if the experiment and control give 
unlike results, we are justified in attributing the 
difference to the unlike factor. 

7. Before beginning an experiment, the object, or aim, 
of the experiment must be clearly conceived and 
clearly stated. The necessary materials and ap- 
paratus should next be decided upon and procured. 
Then may follow the operation, that is, the arrange- 
ment of the materials and apparatus in a suitable 
way. This step is frequently referred to as ^'set- 
ting up" the experiment. The record of it should 
include an accurate statement of the conditions at 
the beginning of the experiment, together with 
drawings of the apparatus and material as the 
experiment is set up. 

Next follows the observation, which must always be 
made and recorded at the time and place of the experi- 
ment. It should include suitable drawings. Fin- 
ally, there may be stated the inference, that is, the 



A LABORATORY GUIDE FOR GENERAL BOTANY 



conclusion or conclusions which are thought to be 
justiJied by the facts observed. 

The record of an experiment, then, should follow 
the outline given below: 

1. Object. 

2. Materials and apparatus (with drawings). 

3. Operation. 

4. Observation (with drawings). 

5. Inference. 

6. Remarks. 
D. The Note-hook: 

8. The Xote-book serves two purposes: First, the 
making of it gives you opportunity to acquire 
facility in describing what you observe. This is 
not an easy accomplishment, but a very essential 
one. ^'The greatest thing a human being ever does 
in this world, ^^ said John Ruskin, "i^ to see something, 
and tell what he saw in a plain way.'^ 

9. Secondly, the note-book serves as an index, to the 
instructor, of what you have done and how well 
you have done it. In addition to these two pur- 
poses, the note-book will be a permanent record 
for your own future use. It should contain a 
complete record of all you observe, and the infer- 
ences vou make from these observations. It should 
include written descriptions and drawings. In 
both the latter the aim should be accuracy, neatness, 
completeness, conciseness. Above aU things, it 
should be a record of your own observation, not 
of your neighbor's. If, as may happen on rare 
occasions, it becomes necessary to use your neigh- 
bor's notes, always state the fact clearly and frankly 
in your own book. 

10. In writing your notes, the aim should be to give 



\ ^ TO THE STUDENT 5 

such a clear account of what you have seen and done 
that anyone else who knew nothing of the subject 
could profit by reading them. In other words, 
aim to make your notes usable in the future. Your 
text-book may be regarded in one sense, as the 
author's laboratory note-book. Seek to make 
your laboratory note-book an accurate and readable 
illustrated text on the ground covered by your 
course. 
E. Laboratory Drawings: 

11. Drawing is one of the greatest aids to observation. 
This is its main purpose in the laboratory. It 
is often said that "persons who cannot draw cannot 
see." This is probably an extreme statement, 
but it is undoubtedly true that one who can make 
an accurate drawing of a thing has observed it 
more accurately than one who cannot. 

12. Laboratory drawings should aim to represent the 
thing only as it is, not as it may impress one at 
first sight. They differ in this respect from the 
work of the artist. For example, to show the 
exact number and location of the veins of a leaf 
would ruin the artist's picture; but without those 
details the laboratory drawing would be of little 
value. 

13. As directed in the Guide, make as thorough an 
observation of the object as possible before you 
begin to draw; then make the drawing. 

14. Unless otherwise directed, make outline drawings, 
shading only where absolutely necessary. In 
general, every line in your drawing should represent 
some fact of structure in the specimen. 

15. Be sure to make the drawing large enough so that 



A LABORATORY GUIDE POR GENERAL B9TANY 

all details may be included without crowding or 
confusion. 

16. First sketch in the outline lightly with a 5H drawing 
pencil. In finishing a 2H pencil may sometimes be 
desirable. 

17. All drawings should be on unruled sheets, and only 
on one side of the sheet. They should be labeled 
and numbered consecutively throughout the course 
by writing under each the abbreviation Fig., 
followed by the proper numerals, and then by the 
legend or label, stating what the object is, and what 
view of it is shown, as for example, '^ Cross-section, 
end view." Each drawing should have all of its 
essential parts labeled by extending straight 
horizontal dotted Knes from the various parts 
(using a ruler), and writing the name of the part 
at the end of the line. 

18. The arrangement of the drawings on the page 
should receive careful attention, so as to make as 
attractive and well balanced a page as possible. 
Crowding should he avoided, and on any one page 
should be included only those drawings that repre- 
sent parts of the same plant, or pertain to the 
same subject. 

19. The various pages of drawings should be numbered 
and labeled near the top of the page at the middle 
thus; Plate I. Throughout your written notes, 
when describing a structure or apparatus repre- 
sented by a drawing, refer to the drawing by its 
proper number and the number of the Plate {e.g., 

Plate IV, Fig. s)- 

20. At the completion of the course, arrange a ^^ Table 
of Contents, ^^ listing the main topics, as indicated 
in the Laboratory Outline, in the order in which 



■* TO THE STUDENT 7 

they occur in the note-book, with the page number 
near the right-hand edge, and a neat dotted line 
extending from the subject to the page number. 
F. The Microscope: 

2 1 . Full directions for the use and care of the compound 
microscope will be given by the instructor. The 
student should clearly realize from the first that the 
science does not reside in the instrument. The latter 
is merely an aid to the eyes, but not to the mind, 
and is made necessary by the limited range of our 
unaided vision. It should be used only after one has 
seen all that he possibly can with the unaided eye. 

22. The following points should be constantly borne 
in mind : 

(a) Keep all parts of the instrument, especially 
the lenses, scrupulously clean. 

(b) Never attempt to take the instrument apart. 

(c) Never remove lenses from the stand. If it 
is ever absolutely necessary to do so, then 

{d) Never lay a lens down on the table. 

(e) Never touch the lens with the fingers or eyelids. 

(/) Never try to clean the lens with the handkerchief 

or anything except lens paper, 
{g) Never examine any object without covering 

it with a cover-glass. 
Qi) Never allow the objective to touch the cover- 
glass. 
{i) Never focus down while looking through the 

microscope, 
(k) Be sure that the slides and covers are absolutely 

clean. Dirt will be magnified as well as the 

object you are studying. 
(/) Handle all slides and cover-glasses by the edge, 

never touching their surface with the fingers. 



8 A LABORATORY GUIDE FOR GENERAL BOTANY 

{m) Don't shut one eye when looking through 
the instrument. Ability to work with both 
eyes open is easily acquired, is much less 
tiring, and is an advantage in many ways. 

{n) Never use high powers when low powers will serve. 

(p) Examine all objects with the low power first, 
then mth the high power, if necessary. 

(p) Never set the instrument away with a micro- 
scopic slide under the objective, nor with the 
high-power objective over the aperture. 

(q) When the laboratory period is over, remove 

the preparation you have been studying, and 

|[leave the microscope either with the low- power 

f objective over the aperture, or, if a dust-proof 

";nose-piece is used, then with the objectives 

sidewise. 



PART I 

ANATOMY AND PHYSIOLOGY 



I. Meaning of the Terms 

A . Plant physiology is that branch of botany which deals 
with the vital activities of plants. But physiological 
processes or functions are carried on by various parts 
of the plant, and these parts all have their own char- 
acteristic structure. In order to understand the proc- 
esses we must know the internal as well as the ex- 
ternal structure of the parts concerned. This knowl- 
edge requires dissection, and this phase of the science 
is, therefore, called anatomy. Microscopic anatomy is 
called histology. Just as the processes cannot be 
intelligently considered apart from the structures 
involved, so, also, the study of anatomy apart from 
physiology is meaningless. 

B. In the lowest (i.e., most simply organized) plants all 
functions, both nutritive and reproductive, are per- 
formed by every structural unit or cell; but in more 
highly organized plants there are special parts or 
organs for the performance of each function; for xe- 
ample, roots to take in moisture, flowers to form seed. 
In other words, in the higher plants there is a division 
of physiological labor, or, as it is sometimes called, a 
physiological division of labor. While not entirely 
wanting, the division of physiological labor is less 
marked in the lowest plants. 

9 



lO ANATOMY AND PHYSIOLOGY 

Because they are composed of organs, plants and 
animals are termed organisms. 
C. Thus we see that some plants have a generalized plant- 
body, others a more highly specialized one. To under- 
stand the various life-processes carried on by plants, 
we must have a knowledge of their structure. A gen- 
eralized plant will be studied first, then the structure 
of a higher {i.e., more highly speciaHzed) plant. This 
will be followed by an elementary study of the funda- 
mental life-processes involved in the nutrition and 
growth of the individual. The second part of the 
course will be devoted to studying the various kinds 
of plants, and the numerous ways in which different 
kinds of plants solve these same life-problems of nutri- 
tion and reproduction. 



II. A Generalized Plant (Spirogyra) 

A . Naked eye Characters: 

1 . Carefully take a small bit of this plant between the 
thumb and fingers and note its ''feel." Suggest 
why it is sometimes referred to as ''green silk.'' 

2. Carefully lift up some of the material with a needle, 
and describe the form of the plant. How many 
centimeters long are the longest filaments you can 
observe? 

3. Can you detect any evidences of a differentiation 
of the plant into shoot {i.e., stem and leaves) and 
root? 

B. Microscopic Characters: 
I. The plant as a whole. 

(a) Mount two or three filaments in water. 

(b) Note that the filament is composed of separate 
structural units, placed end to end. These 
units are cells. 

(c) Are the filaments more than one cell thick? 
Do they branch? Are they of uniform diame- 
ter? Compare the length of the various cells 
with each other. Compare the shape of the 
end cell with that of the others. What is the 
shape of the filament as seen in imaginary cross- 
section? Very careful focussing is necessary in 
order to answer this question correctly. 

(d) Accurately measure the length (in millimeters) 
of a piece of filament lying straight under the 
cover-glass, then count the number of cells in 



12 ANATOMY AND PHYSIOLOGY 

this piece. Calculate the average length of the 
cells, and the number of cells in the longest 
filament observed. Estimate the length of an 
individual cell in terms of its diameter, and from 
this calculate the diameter of the filament, 
(e) Using the low power and removing the cover- 
glass, carefully cut a filament apart with the 
scalpel, causing as little injury as possible. As 
you do this observe the exposed end-walls of 
the uninjured cells that now terminate the fila- 
ment where it was broken apart. Describe and 
try to account for what you see. Is there any 
evidence of the existence of a force w^ithin the 
cell? If so, in what direction does it act? 
Make two outline drawings, showing the con- 
ditions before and after cutting. 
(/) Make a diagram about 75 mm. long, illustrating 
the outline of the three terminal cells of a fila- 
ment, as seen in optical section. Omit all de- 
tails of cell-structure. 
2. The individual cell. 

(a) Center your attention on any one of these cells, 
and identify the following organs of the cell: 
(i) A cell-wall, enclosing all other parts of the 
cell. Is it transparent or not? Give a 
reason for your answer. Note its relative 
thickness. The wall is composed of cellu- 
lose. Has each cell its own end-wall, or is 
there a common end-wall for two adjacent 
cells? 
(2) The substance enclosed by the cell-wall is 
largely Uving matter, or matter in the living 
state. It is called protoplasm. The unit 
of protoplasm of each individual cell is 



A GENERALIZED PLANT 1 3 

called a protoplast. Distinguish the follow- 
ing parts of a protoplast: 

(3) The prominent green chlorophyll-band, or 
chromatophore. Describe its form, the 
number of turns it makes in the cell, and 
the outline of its margin. Infer its shape 
in cross-section. How many bands in each 
cell? If more than one, do they coil in the 
same direction ? Can you detect free ends of 
the chromatophore? Are they continuous 
from cell to cell? The color of the chloro- 
phyll-band is due to the presence of a green 
pigment, chlorophyll. 

(4) The denser areas within the chromatophore 
are regions of starch-formation. In the 
center of this area is the starch-forming 
body, or pyrenoid. Surrounding the pyre- 
noid are starch grains. 

(5) Make a detailed drawing, 10 mm. wide and 
15 mm. long, showing the details of struc- 
ture of a portion of the chlorophyll-band, 
as seen under high power. Indicate on the 
drawing the names of all parts shown. 

(6) At or near the center of the cell find a dense, 
colorless body, the nucleus, surrounded by 
a less dense layer of colorless C)rtoplasm. 
Describe the shape of the nucleus. From 
the layer of cytoplasm trace 

(7) Delicate C3rtoplasmic strands, extending to 
the pyrenoids, and to 

(8) The lining layer of cytoplasm. This layer 
(sometimes called "primordial utricle") is 
in intimate contact with the entire inner 
surface of the cell-wall, and is difficult to 



14 ANATOMY AND PHYSIOLOGY 

detect. Its two surfaces are called plasma 
membranes. 
(9) The clear spaces in the cell are vacuoles, 
filled with cell-sap. 

(10) Make a drawing of a cell at least 10 cm. in 
longest measure, showing all parts. 

(11) The lining layer may be easily demonstrated 
as follows: Place a drop of a 5 per cent, 
solution of common salt (sodium chloride) 
at one edge of the cover-glass. Be careful 
that none of the solution runs over onto the 
cover-glass. By placing a small piece of 
blotting paper at the opposite edge of the 
cover-glass, the water will be removed, and 
the salt solution drawn under the cover- 
glass, irrigating the specimen. Follow with 
another drop if necessary. Observation 
should be continuous while the specimen 
is being irrigated wath the solution. 

(12) Describe the effect of the salt solution on 
the lining layer. 

(13) Loosening the lining layer, as above, is 
termed plasmolysis (i.e., loosening the plasm). 
The cell is said to be plasmolyzed. 

(14) Make a drawing, the same size as the pre- 
ceding, showing a plasmolyzed cell. 

(15) Before plasmolysis the lining layer was held 
close against the -cell-wall with a force, 
already detected (e, p. 12), sufficient to 
cause a rigid condition of the cell called 
tiirgor or turgidity. 

(16) Now replace the salt solution w^th fresh 
tap- water, by the method described in (11) 




A GENERALIZED PLANT 1 5 

above. Describe the effect on the cell. 
What condition has been restored? 

3. Make a diagram, at least 25 mm. in diameter, show- 
ing the appearance of a cell in imaginary cross- 
section taken through the nucleus. 

4. Do you think Spirogyra is a unicellular or a multi- 
cellular plant? If the latter, how many cells con- 
stitute one plant? Give reasons for your opinion 
either way. 

Note. — If time permits, the study of cell-structure may be ex- 
tended by observing the cells in young leaves of Elodea, the skin 
(epidermis) of onion scales, the basal cell of the hairs on any seed- 
ling cucurbit, or the cells of the stamen hairs of Trades cantia. 



III. A Specialized Plant (e.g., The Bean SeedlingY 

A, The plant as a whole: 

1. Examine the seedling given you and note that it is 

composed of an axis with appendages; the axis, of 
root and shoot; the root, of a primary root with 
branches (secondary roots); and the shoot, of a 
main stem, bearing leaves. Has the main stem 
branches? Is this true of all plants? What is the 
difference between a stem and a branch? 

2. Describe fully the location of the leaves and their 

attitude on the stem. Do they occur on both the 
main stem and its branches? The places on the 
stem where leaves grow are nodes. The spaces 
between the nodes are called intemodes. 

3. Compare the size of the upper with that of the lower 

angle made by the leaves with the stem. This 
upper angle is called the leaf-axil (Latin axilla, 
armpit). 

4. Do you find any structures in the leaf-axils? If so, 
describe them. What are they? 

5. With what do the tips of the main stem and branches 

terminate? 

6. Describe any other outgrowths of stem or branches. 

7. Make a drawing of the plant as large as your draw- 

ing paper will permit, showing all parts referred to 
above. 

1 This study may or may not be omitted, depending upon the previous 
preparation of the students, and the time available. 

16 



IV. Structure of the Foliage-leaf (e.g., Lilac 

leaf) 

A. External Characters: 

I. Make a drawing, natural size, showing all the parts 
of the foliage-leaf given you, as seen from the under 
side. 
». Identify the following parts, and label them suit- 
ably on your drawing: 

(a) The fiat, expanded blade. Describe its colora- 
tion (i.e., the kind and distribution of color). 
Is the blade simple (i.e., not divided into leaf- 
lets), or compound (i.e., branched, divided into 
leaflets) ? The surface that lies uppermost, as 
the leaf bends back from its position in the bud, 
is the ventral surface; the under surface is the 
dorsal one. These terms are applied with ref- 
erence to the position of the leaf in the bud. 

(b) The leaf-apex, which is also the apex of the 
blade. 

(c) The margin of the blade. 

(d) The base of the blade. 

(e) The venation (distribution of veins in the blade) . 
Describe it as parallel-veined, pinna tely netted- 
veined (with a midrib), or palmately netted- 
veined. Describe the difference between the 
three types of venation. Is there a marginal 
vein? If so, suggest what advantage it may 
be to the leaf. 

(/) The petiole (stem of the leaf). Leaves having 
a petiole are petiolate, otherwise sessile. 

2 17 



1 8 ANATOMY AND PHYSIOLOGY 

(g) The leaf -base, the portion by which the leaf is 
attached to the branch. 

(h) If present, the stipules, outgrowths of the leaf- 
base. Leaves without stipules are exstipulate. 

(i) Before the next class exercise compare with the 
leaf studied, as directed above, various other 
types of leaves collected by yourself, making 
full drawings and notes. 

B. Anatomy of the Leaf: 

THE LOWER EPLDERMIS^ 

1. As directed by the instructor, remove a strip of 
the lower epidermis of a foliage-leaf, and mount 
it in water or clearing fluid, being sure to have the 
outer surface uppermost. Record the name of 
the species. 

2. Note the cellular structure of the epidermis. A 
group of cells, similar in structure and function, 
is called a tissue. The leaf-epidermis is epidermal 
tissue. The cell-wall forms a box, having depth as 
well as length and breadth. Note that you see 
only the edges of the vertical walls. How many 
walls altogether, bounding each cell? Are they 
visible? Explain. Make a diagram of an epider- 
mal cell as seen in perspective. Are the cell-walls 
transparent or opaque? Give a reason for your 
answer. Suggest the advantage of this feature 
to the plant. 

3. Observe the somewhat lenticular openings, or 
pores, each surrounded by crescent-shaped cells. 

^Miss EcKERSON {Bot. Gaz., 46: 221-224. Si 908) has recommended 
the leaves of the following plants as specially satisfactory for the study 
of the epidermis and stomata: Sunflower, Fuchsia speciosa, zonal Gera- 
mium, and Tradescantia zebrina. 



> STRUCTURE OF THE FOLIAGE-LEAF 1 9 

The openings are stomata (Latin singular, stoma, a 
mouth) . The crescent-shaped cells are guard-cells. 
How many has each stoma? 

4. Do the guard-cells and other epidermal cells contain 
chlorophyll-bodies (chloroplasts) ? Describe their 
shape. They are not considered identical with the 
chlorophyll-band of Spirogyra, hence the different 
name. 

5. Note the shape and arrangement of the other 
epidermal cells. Are they in the same plane as 
the guard-cells? Describe, giving reasons for 
your answer. 

6. State the number of stomata visible in the entire 
field (high power). Record three counts, each 
of a different area, and the average. Why is this 
desirable? After ascertaining the area of the lens of 
the objective of your microscope, calculate, from sev- 
eral counts, the average number of stomata per 
square centimeter. 

7. Make a drawing showing at least three stomata 
with their guard-cells and adjacent epidermal cells. 
The guard-cells should be at least 15 mm. long. 

THE UPPER EPIDERMIS 

8. As directed in B, 1-6 above, study the structure 
of the upper epidermis of the same leaf. Draw. 

9. Compare the structure of the upper with that of 
the lower epidermis, noting, among other features, 
the relative number of stomata in each. 

10. In the hght of the experiments on transpiration,^ 
what do you think is one function of these stomata? 
Of the guard-cells? 

^ This takes for granted that class demonstrations of transpiration 
have been given. 



20 ANATOMY AND PHYSIOLOGY 

11. Give one explanation of the difference in the rate 
of transpiration from the two surfaces of the leaf. 
Is this the only explanation? 

CROSS-SECTIONAL VIEW 

12. Mount thin free-hand sections of a fresh leaf show- 
ing the internal anatomy as seen in cross-section. 

13. Identify in your section the two epidermal layers. 
How many cells thick are they? Do you find 
any chloroplasts in these layers? 

14. Are all the epidermal cell- walls of the same thick- 
ness? Describe any variations observed. 

15. Is there a thick, continuous pellicle over the surface 
of the leaf? Is it composed of cells? Such a 
pellicle, when it occurs, is called cuticle, and is com- 
posed of a waxy material, cutin. 

16. Compare the thickness of the cell- walls in the upper 
and the lower epidermis. 

17. Note the stomata and guard-cells, and their relation 
to the other epidermal cells. 

18. The tissue between the two epidermal layers is 
composed chiefly of leaf -parenchyma, ormesophyll, 
in which are imbedded the veins. Mesophyll, and 
all other tissue containing chlorophyll, whether 
found in leaves or in other organs, is also called 
chlorenchyma. Note that the mesophyll is com- 
posed of two distinct groups of cells, as follows: 

19. The more compactly lying cells beneath the upper 
epidermis compose the palisade layer, or palisade 
parenchyma. Describe their shape, contents, rela- 
tive size, and relation to each other and to the 
epidermis. 

20. Between this layer and the lower epidermis lies the 



■* STRUCTURE OF THE FOLIAGE-LEAF 21 

Spongy parench5nna. Describe its appearance, and 
the cells that compose it. Compare it with the 
palisade layer. 
21. What fills the space between the mesophyll-cells? 
Do these spaces connect with the outside air? 
If so, how? 

THE VEINS 

2 2. At certain regions the section passes through veins, 
presenting either cross, longitudinal, or other 
sections of them. Note the greater differentiation 
' of the cells in the veins. This differentiation marks 
the distinction between fundamental tissue or 
parench3mia, and transformed, elongated tissue, 
prosenchjrma. There are several different kinds of 
prosenchyma. 

23. Using prepared slides, supplied by the instructor, 
make a drawing of the cross-section of a leaf, show- 
ing all features noted above. Make the drawing 
at least 75 mm. long, and be careful to preserve the 
natural proportions. 



V. Traxsplel-vtiox^ 

A . Loss of Weight of a Grouing Plant: 

Experiment i. — Object:- To show that a living plant 

is constantly losing weight. 
I. Choose a well- watered, \-igorous, potted plant. 
Wrap the pot in sheet rubber or oilcloth (or paraf- 
fined paper\. and tie the wrapping about the stem 
tightly, but not tightly enough to cause injury. 
Place the plant thus prepared on a pair of balances 
in a well-lighted window, and record its exact 
weight in grams in the following table, which should 





Time 




Weight in 
grams 


Day 




Hour 


i 



be copied into your note-book. After weighing, 
the window should be opened (if the weather is not 
too cold) ; direct sunlight is also desirable. Record 

^ Note. — Where the class is large, or the laboraton.- equipment limited, 
and especiall}' when the course extends over only one semester, it is rec- 
ommended that most, if not all, of the phj=^ioIogical experiments outlined 
in the remainder of Part I be performed by the instructor as demonstra- 
tions in the presence of the class. 

* For directions for recording an experiment see p. 4 of this Guide. 
In each experiment this outline is to be filled out entire, without further 
directions. 



I 



22 



> . TRANSPIRATION 23 

the weight at five or six successive periods, and then, 
as directed by the instructor, plot on section-paper 
a curve of your readings. Lay off the observed 
weights as ordinates, the time-intervals as abscis- 
sae. Be sure that in this and all subsequent ex- 
periments your inferences are only those warranted 
hy your observations. 
Experiment 2. — To ascertain one cause of loss of weight 
of plants. • 

1. Take four clean, dry glass beakers or tumblers, two 
pieces of cardboard large enough amply to cover the 
opening of the beaker, and a vigorous green leaf 
having a leaf- stalk and a perfectly dry surface. 

2. Fill two of the glass beakers or tumblers three- 
fourths full of water, insert the leaf-stalk through 
a small hole in the center of one piece of cardboard, 
make the opening as tight as possible about the 
leaf-stem, using cotton if necessary, and place the 
cardboard over one of the water-containing beak- 
ers, so that the leaf-stalk extends down into the 
water. Invert one of the dry beakers over the leaf. 
Arrange the other two beakers and cardboard in 
the same way, only omitting the leaf and the hole 
through the cardboard. This second set of beak- 
ers is the control {cf. p. 3, 1(6). 

3. Place both sets of beakers in a well-lighted window, 
preferably in direct sunlight, and from time to time 
observe and compare the appearance of the inner 
surfaces of the inverted beakers. 

4. Do you notice any difference in the result ori oppo- 
site sides of the leaf? If so, describe. 

5. Can you see any water passing from the leaves? 
In what state, therefore, does it pass off? From 
what part of the leaf does it come? Why do you 



24 



ANATOMY AND PHYSIOLOGY 



B. 



think so? What change does it undergo in order 

to become visible on the surface of the beaker? 

In what state does it probably exist in the leaf? 

State one reason why the plant lost weight in 

Experiment i. Was this the only cause of its loss 

of weight? 
6. The above experiments demonstrate the fact of 

transpiration. Give a definition of transpiration. 
The Control of Transpiration: 
Experiment 3 . — To see if the epidermis affects the rate 

of transpiration. 
I. Take two sound apples. Remove the skin (epider- 
- mis) from one of them, then ascertain accurately 

and record the weight of each, in tabular form, as 

follows : 



Time Weight in grams 


1 
Day Hour 


Unpared 


Pared 











2. Place the specimens in a convenient place, with free 
access of air, and out of reach of mice. 

3. Record, in a table like the above, three (or more) 
subsequent observations of weight at successive 
class periods. 

4. Plot two curves showing the rate of loss of weight. 
Include these curves and their interpretation as 
part of your record of the experiment. 

Experiment 4. — To demonstrate the effect of the 
*'skin" of a potato-tuber on transpiration. 



TRANSPIRATION 25 

1. Proceed as directed for Experiment 3, using two 
sound potatoes instead of apples. 

2. The ''skin" of an apple is a true epidermis, having 
an outer layer of cuticle, which is not readily per- 
meable by water. The ''skin" of a potato-tuber 
consists of several layers of cork cells. It is this 
corky tissue which chiefly retards the loss or water 
from the tubers. 

Experiment 5. — After noting the color change caused 
by wetting dry cobalt paper (prepared by dipping 
filter paper into a solution of cobalt chloride and 
thoroughly drying it), make the following experi- 
ment: Place discs of the cobalt paper {e.g., as 
large as a five cent piece) on opposite sides of a 
lilac leaf, and hold all in place between two micro- 
scopic slides (or larger pieces of glass), fastened 
with rubber bands around each end. Compare the 
rate of color change of the two opposite discs, and 
infer the cause. 

Other leaves, having structural peculiarities 
similar to those of the lilac, may be used; e.g., 
hibiscus, osage orange, oleander, lizard's tail 
(Saururus) . 

Experiment 6. — Examine, with the microscope, strips 
of both upper and lower epidermis of the leaf used 
in Experiment 5, and infer the probable cause of 
the differential color-change observed. 

Experiment 7. — Place any suitable, well-watered potted 
plant on postal scales, "household" scales, or other 
convenient weighing device, after first carefully 
wrapping the pot in sheet-rubber, or sheet-oil- 
cloth, as in Experiment 1 . Record the loss of weight 
at fifteen-minute (or other suitable) intervals while 
the experiment is standing for an hour, each, in {a) 



26 ANATOMY AND PHYSIOLOGY 

direct sunlight and breeze; (b) diffuse sunlight, and 
the comparatively still air of a room; (c) under a 
glass bell-jar, or largt box. The breeze may be 
secured by placing the experiment in or near an 
open window or other draught, or by means of an 
electric fan. 

On the basis of your observations in Experiment 7, 
discuss the control of transpiration by external 
conditions, and suggest differences in the condition 
of the plant caused by its exposure in the various 
situations suggested above, and the eff'ect this would 
have on the rate of transpiration. Were the results 
observed in the three situations strictly comparable? 
Why? 
C. One Ejffect of Transpiration: 

Experiment 8. — To show the so-called "lifting power'' 
of transpiration. 

1. Insert a leafy stem of a hving plant (a branch of any 
evergreen is excellent to use) into one end of a piece 
of glass tubing about 3 ft. long, of small bore, and 
full of tap-water, taking special care to have the 
joint between the stem and the glass air-tight, 
using rubber tubing for this purpose if neces- 
sary. The experiment will be more satisfactory 
if the stem is cut off under water, and the cut 
end kept from contact with air, throughout the 
experiment. 

2. After being sure that the glass tube is full of water, 
place it upright in a dish of mercury, having care 
not to allow any of the water to run out in so doing. 

3. Place the experiment in sunlight, if possible, but 
do not leave it in direct sunlight for more than one- 
half to three-quarters of an hour. 

4. At the beginning of the experiment, and at suitable 



* TRANSPIRATION 27 

intervals thereafter, as directed by the instructor, 
measure and record the height of the mercury in 
the glass tube. 

5. Make two drawings of this apparatus in longitudi- 
nal section: (a) as soon as the experiment is set up; 
(b) at the close of your final observation. Label 
all essential parts. 

6. You have made this last experiment with a living 
plant. The question now naturally arises: Is the 
result observed due to the life-factor involved, or 
is it merely the result of some physical condition, 
as, e.g., the evaporation? The question may be 
easily answered by setting up an experiment similar 
to the preceding, but using non-living material, 
as follows: 

Experiment 9. — To see if evaporation exerts a ''lifting 
power." 

1. Tie a piece of porous animal membrane {e.g., bladder) 
over a thistle-tube, being sure that there is no 
chance for a leak between the glass and the 
membrane. 

2. Fill the thistle-tube with water. 

3. Prepare a dish of mercury and also a clamp to hold 
the tube in place. 

4. Invert the thistle-tube and place the lower end in 
the mercury, being sure that no air enters the tube. 
By this arrangement all factors of Experiment 8 
have been eliminated except evaporation, and the 
evaporation takes place through only one mem- 
brane, and that a non-living one. In other words, 
we have Experiment 8 reduced to its lowest terms. 

5. Observe and record the heights of the mercury in 
the tube as in Experiment 8. 



28 ANATOMY AND PHYSIOLOGY 

6. Make a drawing of this apparatus in longitudinal 
section at the beginning and at the close of the 
experiment, labeKng all essential parts. Jj 

7. The conclusions drawn from this experiment should 

cover an explanation of the bearing of these results i 

on Experiment 8. 

8. The experiments on transpiration have shown that 
living plants are constantly losing water. What 
would be the result if no more were supplied? 
What problem of plant life, therefore, naturally 
arises? 

i 



VI. Absorption of Water by Plants 

A. External Anatomy of the Root: 

1. Examine roots of seedlings (mustard, flax, oats, 
etc.), grown in a moist chamber (e.g., flower-pot, 
or saucer of same) in the dark, and kept covered 
with a glass plate so as to expose them to the air 
as little as possible. Note the delicate white hairs 
on them. Describe their distribution and relative 
size. These hairs are root-hairs. 

2. Hold the root up to the light and note the more 
transparent tissue on the end (root-cap), covering 
the root-tip proper. How is the latter distin- 
guished? Is ''root- tip" synonymous with ''end of 
the root?" Explain. 

3. Make a drawing of the seedling, at least twice 
natural size, showing these features. (The labeling 
of the root-cap and root-tip may be deferred until 
observation B, 3, below, has been made. ) 

B. Microscopic Characters of the Root: 

1. With the scalpel carefully remove the terminal 
5 to 6 mm. of a root, with the root-hairs, and mount 
it in water. Locate the oldest and youngest root-: 
hairs. How are they distinguished? Do they 
branch? What relation do the hairs bear to the epi- 
dermis ? Are they divided by cross-walls ? Do they 
contain nuclei? What is a root-hair, structurally? 

2. Make a drawing (high power) of three or four hairs, 
showing their structure and relation to the epider- 
mis. The hairs should be drawn at least 50 to 75 
mm. long. 

29 



30 ANATOMY AND PHYSIOLOGY 

3. Distinguish the root-tip from the root-cap. Of 
what is the latter composed? Describe it. Draw. 

C. The Function of Root-hairs: 

1. Carefully pull up a mustard seedling growing in 
sand and having several leaves. Without injuring 
the plant, carefully and very gently shake off all 
sand that readily falls away. Does the sand adhere 
with equal firmness to all portions of the root? 
Describe in detail, explain, and illustrate by a 
drawing, X2. 

2. Pull up another seedling of the same age, and remove 
all or most of the adhering sand. Replant both 
seedlings in sand, water them, and set them aside 
until the next period. In order to eliminate indi- 
vidual differences it is necessary to treat several 
seedlings in each of the ways above indicated. 

3. At the next meeting of the class observe and com- 
pare the appearance of the seedlings. In thor- 
oughly removing the sand from the seedlings, how 
were the root-hairs affected? 

4. By means of what organs does a land plant obtain 
most of its water? State, in a paragraph, the 
reasons for your answer. 

5. We have ascertained the organs whose function 
it is to take in water from the soil. It is now 
important to inquire by what process the soil- 
water passes into the plant through the organs 
of absorption. 

D. How the Root-hairs Take in Water; Osmosis: 

I. The preceding studies of the plant cell lead us to 
recognize the fact that the root-hair is abrancli of the 
epidermal cell. Within is the cell-sap, a weak solution 
of various salts, sugars, and other substances; with- 
out, as the plant grows in the soil, is the soil- water, 



ABSORPTION OF WATER BY PLANTS 3 1 

also containing numerous substances in solution. 
The cell-sap of the root-hairs and the soil-water 
are solutions of different densities, and separated 
by layers of porous (semipermeable) plant substance. 
Name these layers. 
Experiment lo. — To see what results when two liquids 
of unequal density are separated by a porous mem- 
brane: 

2. With a pen knife or a pair of scissors, remove a 
portion of the shell from the large end of a hen's 
egg, taking great care not to puncture the mem- 
brane that separates the white of the egg from the 
shell. 

3. Carefully place the ^gg thus prepared upright in 
a glass tumbler, or beaker, and pour in tap-water 
until the water surface is about i in. above the egg. 

4. By the above arrangement the solution of various 
salts intermingled with the substance of the Qgg 
serves as the more dense liquid, the water outside 
as the less dense, while the membrane in the egg 
acts as the porous membrane, separating the two 
liquids. In other words, we have roughly imitated 
the plant cell, though there is nothing in the cell 
that corresponds to the shell of the egg. 

5. Make a careful drawing, showing the experiment 
in longitudinal section, and about one-half natural 
size. Label all parts. 

6. Make an observation at the end of an hour; of 
two hours. Describe what results, and illustrate 
the final result by another sectional drawing 
opposite the first one. 

7. State as clearly as you can what has taken place 
in order to produce the result observed. The 
process is termed osmosis (Greek, osmos, pushing). 



32 ANATOMY AND PHYSIOLOGY 

8. In this experiment, what part of the root-hair 
does the egg membrane represent? the solution of 
salts in the egg? the water in the beaker? 

9. From the above study explain what takes place 
when a root-hair is in moist soil. What is thus 
accomplished for the plant? 

10. Define osmosis. 

Experiment 11. — To demonstrate osmosis in a plant 
cell: 

11. Mount in water several uninjured root-hairs. 
Again identify (high power) the lining layer of 
cytoplasm. Make a drawing, about 50 mm. long, 
of one of the root-hairs. Leave room for two 
other drawings by the side of the first one. Run 
a drop of a 5 per cent, salt solution under the 
cover-glass. This solution is more dense than the 
cell-sap. 

12. Describe the effect of the salt solution on the proto- 
plast. 

13. Make a drawing by the side of the first one, showing 
what you observe. What is the process called? 

14. Now thoroughly irrigate the cells with fresh water, 
and observe and describe the results. Explain as 
fully as you can. 

15. By the side of your second drawing make a third, 
showing the cell as it appears after irrigation with 
fresh water. 

16. In a sentence, name, in order, two processes that 
take place, {a) when a living plant cell is immersed 
in a solution more dense than the cell-sap ; {h) when 
a plasmolyzed cell is irrigated with tap-water. 

17. What is one function of the substances dissolved 
in the cell-sap? What is one function of the plasma 
membrane? 



■V ABSORPTION OF WATER BY PLANTS 33 

Experiment 12. — Demonstration of the Osmoscope 
(by the instructor) . * 

18. Make a drawing showing clearly all essential parts 
as seen in longitudinal section, and describe the 
apparatus as set up and explained by the instructor. 

19. Record observations on the height of the column 
of water in the tube of the osmoscope : 

{a) At the beginning of the experiment. 
{h) On successiv-e half-hours. 
{c) On successive days. 

20. Explain the results observed. 

Experiment 13. — Demonstration of "exudation-pres- 
sure" (by the instructor). 

21. Describe and make a drawing of the experiment at 
its beginnings as set up by the instructor. 

22. Complete your observations and record as directed 
under Experiment 12, naming the species of plant 
used. 

23. Compare the conditions and results in this experi- 
ment with those in Experiment 12. 

*It is here taken for granted that the instructor will be able to make 
this demonstration (as well as that under Experiment 13) without further 
suggestions, using any one of the various types of osmoscope commonly 
found in botanical laboratories. 



VII. The Path of Water in the Plant: Structure 

OP Stems* 

A . The Function of the Stem: 

Experiment 14. — To see if there are definite channels 
for the passage of Liquids through a stem. 

1. Place the cut ends of various li\-ing, leafy shoots 
(e.g., corn, plantain, lily leaves, parsnip, or seed- 
lings of castor-oil plants), into an aqueous solution 
of eosin, and, after they have stood for a suitable 
time, as determined by the instructor, observ^e 
freshly exposed end-surfaces, and note the regions 
where the colored solution appears. Does it pass 
up through the whole mass of tissue, or are there defi- 
nite channels through which it rises? Cut sections 
of the stems at various heights, and observe and 
describe the distribution of the colored areas. 

2. Compare the distribution of the colored areas in a 
parsnip (or seedling of a castor oil plant) and a 
stalk of com (or petiole of some Hly leaf). Make 
a diagram to illustrate this. 

3. Examine the end of a dry corn stalk, and note the 
projecting strands. What relation do they bear to 
the paths of the eosin? They are composed of 
fibers and vessels united, and are therefore caUed 
fibre -vascular bundles. To what class of tissue 
do they belong? 

4. CarefuUy cut the epidermis in a ring around the 
petiole of a leaf of plantain, being specially careful 
not to cut clear through the petiole. 

*The outline for §^^1, B-F (pp. 35-41), was prepared by Prof. Ernest 
Shaw Re>Tiolds, Agricultural College, N. D. 

34 



STRUCTURE OF STEMS 35 

5. Taking the end of the petiole in one hand and the 
leaf-blade in the other, gently pull the two portions 
of the petiole a short distance apart. Describe and 
illustrate by a drawing what you observe. What 
structures are thus disclosed? 

6. What relation do the fibro- vascular bundles bear 
to the veins of the leaf? To the root-hairs? 

7. Write a clear statement of how the water passes 
from the soil into the roots of a plant, and into and 
through the leaves and out into the air, mentioning, 
in order, all parts and processes studied. 

B. Internal Structure of an Endogenous (Monocotyledonous) 
Stem: 
I. "Examine with your naked eye a thin cross-section 
of a corn stem. What general features are to be ob- 
served? What relation do the dots, seen in this 
cross-section, bear to the fibro-vascular bundles? 
What then are these dots? Now study the section 
under the hand lens and compare the number of 
bundles near the center and near the periphery. 
Where are they most numerous? What mechanical 
advantage do you see in the observed arrangement 
of the bundles? The cells intermixed with the bun- 
dles are ^^7/5 cells. What kind of tissue? How far 
from the center do they extend toward the periphery? 
2. Make a drawing of the cross-section, as seen under 
the hand lens, about 10 cm. in diameter, then ex- 
amine the section under the microscope. Illustrate 
with a drawing at least 12 cm. wide, the cross-section 
of a vascular bundle located near the center of the 
stem. The yellowish ring of cells around the out- 
side of the bundle is the bundle sheath. What 
features of the sheath make the color so noticeable? 



36 ANATOMY AND PHYSIOLOGY 

The bundle sheath surrounds tissues in which there 
are three or four large open spaces: (i) The some- 
what irregular space at one end is an intercellular 
air passage; (2) the two on either side of the middle 
are trachece. A ring from an annular tracheid may 
often be seen projecting into the inner end of the air 
passage; and one or more spiral tracheids may 
lie between the two large tracheae. This group 
of tracheae and tracheids constitutes the xylem, 
or water-conducting tissue. It is woody in con- 
sistency. The thin-walled, closely packed tissue, 
at the opposite side of the bundles from the air 
passage, is the phloem tissue, which under high 
power can be seen to be composed of two kinds of 
elements: (i) The larger cell-Hke spaces which are 
cross-sections of the sieve-tubes; and (2) the very 
small, nearly square cells, at the corners between the 
sieve-tubes, which are the companion cells. The 
phloem is concerned in the conducting of elaborated 
food, perhaps chiefly the nitrogenous foods. Com- 
pare the vascular bundles near the periphery with 
those at the center of the stem. What differences 
are there in structure, and in the relation of one 
bundle to another? How are the xylem and 
phloem placed in the bundle in relation to the 
periphery of the section? 
3. Examine a longitudinal section of a corn stem of 
considerable length and make a diagram illustrating 
the course of the vascular bundles, especially notic- 
ing how and where the bundles (veins) from the 
leaf enter the stem and the course they take. What 
finally becomes of the leaf -bundles ? 



■" STRUCTURE OF STEMS 37 

C. Internal Structure of Herbaceous Exogenous {Dicoty- 
ledonous) Stems: 

1. Cut some very thin slices of wood and mount one 
piece in anilin sulphate and one, after it has been 
moistened with hydrochloric acid, in a solution 
of phloroglucin (warming the slide, if necessary, to 
develop the color). What colors are developed in 
the wood in each of the solutions? (Compare with 
one in water.) These color reactions are very char- 
acteristic of lignified (woody) cell-walls, although 
anilin sulphate also stains some fibers in other than 
wood regions. 

2. Now cut thin cross-sections of some herbaceous 
exogenous (dicotyledonous) stem (g.^., garden gera- 
nium). Mount these sections, some in anilin sul- 
phate, some in phloroglucin after HCl, and some in 
water, for microscopic examination. These should 
show which parts of the herbaceous stem are 
lignified. Where are these lignified (xylem) por- 
tions, and how many are there in the stem? Was 
it easier to cut these or the wood sections? Why? 
The mass of tissue directly outside of each wood 
(xylem) region is the phloem tissue of the vascular 
bundle. Between the xylem and the phloem in each 
bundle observe a layer of one or two cells of cambium, 
an actively dividing tissue that produces more xylem 
and phloem. How are the bundles arranged in the 
stem? The tissue between the bundles and the 
periphery of the stem is composed of cortex, covered 
on the very outside with the epidermis. 

3. Study these sections under the microscope and com- 
pare them with the corn stem. Do you find the 
same tissues in both cases, or with what exceptions? 
How do they differ in arrangement? What would 



38 ANATOMY AXD PHYSIOLOGY 

you consider the chief stnictural distinctions 
between the corn stem and this herbaceous stem? 
4. Make a diagram of the cross-section as seen under 
the hand lens, labeling the tissues as thus seen. 
It is to be noted that endogenous (monocot>dedo- 
nous) herbaceous stems are essentially like the corn 
stem in cross-section. 
D. Primary Growth in a Woody Exogenous (Dicofyledanous) 
Stem: 

1. Examine with a hand lens a cross-section of a young 
Aristolochia, or other woody stem, which has not 
yet developed tissue from the cambium layer. 
The arches of tissue near the periphery (in Aristolo- 
chia), as seen under the hand lens^ form the outer 
boundary" of the vascular bundles. How and where 
are the latter arranged ? How many are there in the 
whole cross-section? In what general respects 
does this stem differ from that of the corn? How is 
it like the herbaceous stem? Make a diagram of 
the section. 

2. Examine the section under the microscope. The 
bundles are seen to be somewhat wedge shaped. 
The inner part is the x}dem, and the outer (toward 
the periphery') the phloem. The x}dem is recognized 
by the large tracheae. The cambium is also present. 
Where would you look for it? ^lake a careful 
drawing of a portion of the cross-section, including 
one complete bundle and at least a quarter of each 
bundle on each side; this will be a V-shaped sector 
with the point at the center of the stem-section and 
the arc at the periphery. Radiating from the center 
and between each pair of bundles are the medullary 
rays. How are these related to the pith at the cen- 
ter? Into what tissue do they merge toward the 
periphery? The xylem is composed of the tracheae, 



STRUCTURE OF STEMS 39 

tracheids, and wood parenchyma. The phloem is 
similar to that of the corn stem. Outside of the ring 
of vascular bundles is the pericycle, and outside of 
that the cortex, both of the latter often becoming 
changed into dead bark eventually. On the very 
outside is the epidermis. Under the high power of 
the microscope determme how the epidermis is pro- 
tected against excessive evaporation. About how 
many rows of cells are there in each of the tissues: 
epidermis, cortex, and pericycle? 
3. Is there any fundamental difference between the 
young woody stem and an herbaceous stem? The 
arrangement and structure of the bundles in the corn 
stem are characteristic of the endogenous (mono- 
cotyledonous) type of stem, and the arrangement 
and structure of the bundles in the herbaceous and 
woody stems are characteristic of the exogenous 
(dicotyledonous) type of stem. 
E. Secondary Growth of an Exogenous {Dicotyledonous) Stem: 

1. Examine a thin cross-section of an Aristolochia, 
or other dicotyledonous stem, wliich is 3 or 4 years 
old. A hand lens view of this is to be drawn, indi- 
cating clearly the chief regions, pith, wood, and bark. 
Do you find concentric rings in the wood? How 
far apart are they and how many are there? These 
are the ''annual rings,'' which indicate the number 
of periods of growth through which the stem has 
passed. Each ''ring" is, of course, the end (cross- 
section) of a roughly cylindrical layer of tissue 
formed during a given period of growth. 

2. Now study the cross-section under the microscope, 
and make a V-shaped drawing of a portion of the 
section, showing samples of each kind of tissue 
in proper position. What characteristics mark 



40 AXATOiTY AND PHYSIOLOGY 

the end of one period of growth of xylem (wood) 
and the beginning of the next? State clearly the 
differences between the stem at this age and at the 
age when there is primary growth only. Outside 
of the wood zone there is the zone of "inner bark." 
Wliat other term is applied to this tissue? Can 
you distinguish the cambium layer? Where is its 
exact location? How do the cells immediately 
on each side of it differ from the cambium cells? 
Notice particularly the medullary rays. How 
numerous are they? Remembering the special 
properties of cambium, what explanation can you 
give for the large amount of wood, the complete 
layer of phloem, and the numerous medullary rays? 
Do all the rays reach the pith? If not, how far 
do they reach; and how far do they extend toward the 
periphery? Are they alike in this respect? How 
do you account for this condition when compared 
Tvith the distance the medullary rays extend in 
primary growth? Can you distinguish separate 
vascular bundles in this stem? WTiat has caused 
the difference between this stem and the young 
A ristolochia stem in this respect ? How many differ- 
ent tissues do you find in the bark region, and what 
characteristics does each show? 
3. Compare a longitudinal section of this same stem 
^ith the cross-section just studied and distinguish 
each tissue. Notice especially the tracheae. How 
are they better constructed to give rapid transfer 
of water than the other parts of the stem ? Note the 
tracheids (long cells with sharp ends). Are they 
parenchymatous or prosenchjTiiatous? Why? 
Make a list of the various tissues of the stem and, 



STRUCTURE OF STEMS 



41 



opposite each, state what types of cells are found 
in each tissue. 
4. Make a diagram of a stem 4 years old, clearly indi- 
cating the corresponding years' growth in phloem 
and in xylem, and showing some medullary rays for 
each year's growth. This should be a cross-sec- 
tional diagram, drawn not less than ten centimeters 
in diameter. 
F. Comparison of Stem Structure: 

Copy the following table into your note-books and 
indicate the presence of the characteristics by a 
cross under the proper heading, and opposite the 
name of the plant which shows the characteristic. 





S 


B 


PL, 


6 

B 
a 



w u 
a, (u 


'd'o 
pq 


Secondary 
growth 


u 

m 


u 




4) 

'a 


Corn Stem 






















Aristolochia less than 
one year old. 






















Aristolochia 3-4 years 
old. 














— - 




— 




Herbaceous Stem 

















VIII. Mechanical Uses op Water in the Plant 

A . Rigidity and Maintenance of Form: 

Experiment 15. — To ascertain the cause of rigidity in 
beet tissue: 

1. From a beet cut four slices about 5 mm. thick, 
10 mm. wide, and 75 mm. long. 

2. Place the slices as follows: 

(a) In tap- water. 

(b) In a 10 per cent, salt solution. 

(c) and (d) In boiling water for two or three min- 
utes. 

Then place 

(c) In tap-water, and 

(d) In the 10 per cent, salt solution. 

3. At the end of fifteen minutes observe and record 
the relative rigidity of the various slices, ascer- 
tained by carefully bending them. 

4. Thoroughly rinse the slices, b and d, and then 
transfer them to tap-water. At the end of an 
hour (or sooner) observe them again and describe 
the result. 

5. Explain your observations on the basis of your 
previous experiments. 

6. What is one mechanical use of water in a plant 
tissue, and how is this accomplished? 

Experiment 16. — To demonstrate longitudinal tissue- 
tension. 

7. Obtain a petiole of rhubarb, or burdock, or a 
stalk of celery. With a scalpel make a lengthwise 

42 



■'MECHANICAL USES OF WATER IN THE PLANT 43 

cut for a distance of about 25 mm. from the end, 
and just beneath the surface. 

8. Describe the position assumed by the severed piece. 
Illustrate by a diagram, natural size. 

9. From another petiole cut off a portion at least 
15 cm. long, with the cut surfaces normal to the 
edges. Record the exact length of the piece in 
millimeters. 

10. With a scalpel carefully remove a thin strip of 
outer tissue along the entire length of the piece 
(or remove a strip of ''bark" from a very young 
woody stem). At once try to replace it. Has it 
altered in length? If so, describe. Make another 
similar observation at the end of ten or fifteen 
minutes. What would you have to do to the 
strip to make it resume its former length? 

11. Carefully measure the length of the excised strip 
about fifteen minutes after its removal. Record 
this measure, and calculate the percentage of change 
in length. 

12. From another portion of the petiole cut off two 
strips from opposite sides (or the bark from a 
portion of some young woody stem). Place one 
of the excised strips in water, another in a 10 
per cent, salt solution. 

13. At the end of five or ten minutes compare the 
lengths of the two strips, {a) with each other, 
{h) with the portion of the stem from which they 
were cut. Explain what you observe. 

14. From the preceding studies describe the condition 
of the tissues in a plant stem. To what is this 
condition due? 

15. Of what advantage do you think this condition 
would be to the plant? 



44 AliATOMY AND FEraSIOUOGY 

Experiment 17. — To demonstrate transvo^e tissue- 
tension. 

16. Take short portions (about 15 or 20 nun. long) 
of some woody stem 15 to 20 mm. in diameter, 
and with the scalpel make a dean cut lengthwise 
through the bark, and remove the bark, being 
careful not to crack or break it. 

17. At once, or at the end of four or me minutes, 
try to replace the bark. Describe your success 
in so doing. Draw, end view and side view. 

18. What must be done to the bark in order to restore 
its original length? 

iG. F: : ri- this study what further do you know of the 
condition of the tissues in a plant stem? Explain. 



IX. Nutrition 

A. The nutrition of plants is very similar to that of 
animals, with the exception that all green plants 
manufacture their food out of inorganic chemical com- 
pounds. Animals cannot do this. They must conse- 
quently receive their food ready-made. But there are 
some lower organisms (doubtfully animals) that pos- 
sess the ability to elaborate their food out of inorganic 
compounds, while on the other hand, certain plants, 
such, for example, as the mushrooms and other plants 
wanting chlorophyll, lack this power. 

B. The manufacture of carbohydrates is, in many respects, 
the most important function of green plants. With- 
out it all life would be impossible, so that its study 
becomes of very great interest. We will first learn 
how to detect the presence of a carbohydrate such as 
starch, then study its occurrence in plants, and finally 
the process by which it is made out of simpler chemical 
compounds. 



45 



X. The Occurrence of Carbohydrates in Plants 

A . The Test for Starch: 

Experiment i8. — To ascertain the test for the pres- 
ence of starch. 

1. Place a bit of corn starch, about the size of a small 
shot, into a test-tube one-fourth full of water. 
Shake it thoroughly. Is starch soluble in cold 
water? Give a reason for your answer. 

2. Bring the starch mixture to a boil over the flame 
of an alcohol lamp, or Bunsen burner. Describe 
the result. Is starch soluble in hot water? Give 
a reason for your answer. 

3. Set this test-tube aside to cool for a moment or 
two. 

4. Into a test-tube one-fourth full of clear water 
place 3 or 4 drops of iodine solution, using a pipette. 
Shake the mixture and describe the color. 

5. Now place i or 2 drops of the iodine into the 
cooled, boiled starch mixture. Shake the mixture 
and describe the resulting color. 

6. Pour one-half of this mixture into another test-tube 
one-half full of water. What color appears? 

7. Describe a test for the presence of starch. (Note: 
The iodine is not the test; it is * only the reagent 
used.) 

Experiment 19. — To see if there is starch in (a) seeds; 
ih) stems; {c) roots. 

8. Boil in water, in a test-tube portions of the above- 
mentioned parts of plants, and proceed with the 

46 



> . OCCURRENCE OF CARBOHYDRATES IN PLANTS 47 

starch test, as above outlined. Record the experi- 
ment as usual. Be careful to distinguish between 
your observations and your inferences. 

Experiment 20. — Microchemical tests for starch. 

9. If time permits of individual tests by the student, 
microchemical tests may be made by mounting in 
water, on microscopic slides, small portions of, 
first, commercial starch; second, material scraped 
from any soaked seeds {e.g., corn, bean), a potato- 
tuber ( a stem), any convenient fleshy root, in each 
case observing (and drawing) the shape, surface- 
markings, and characteristic groupings of the starch 
grains, then running under the cover-glass a drop 
of iodine solution, and observing the color reaction. 

Experiment 21. — To see if there is starch in leaves. 

10. Extract the chlorophyll from leaves of nasturtium, 
bean seedling, or other covenient large-leaved 
plant, by placing the leaf first in hot water to facili- 
tate the extraction; second, in hot alcohol, or, after 
they have been dipped in hot water, the leaves may 
be left in cold 80 per cent, alcohol until the following 
class period. 

11. Describe the effect of the alcohol on the color of the 
leaf, and state your inferences as to the solubility 
of chlorophyll. 

1 2 . Place the leaf in a watch-glass, and irrigate it 
with iodine solution. After a few moments pour 
off the iodine, and observe the color of the leaf. 
This last observation is often made more striking 
by placing the leaf on a small piece of glass, and 
holding it to the light. State your inferences from 
this observation. 

13. If preferred, de-chlorophyllized leaves may be cut 
into small pieces, boiled in water in a test-tube over 



48 ANATOMY AND PHYSIOLOGY 

a Bunsen flame, and the water then tested for the 
presence of starch. 
B. Test for Sugar: 

1. We have seen that starch is a practically insoluble 
carbohydrate. We also know that sugar is a read- 
ily soluble carbohydrate. The chemical formula for 
a molecule of starch is CeHioOs. If we combine 
with this molecule one molecule of water (H2O) we 
have a molecule whose composition is represented 
by the formula C6H12O6 [(C6Hio05)n + H2O = 
C6H12O6]. This is grape sugar. Sugar, then, differs 
from starch in possessing relatively more hydrogen 
and oxygen in its molecule. The process of con- 
verting starch into sugar is termed hydrolysis, and 
since it converts an insoluble substance into a 
soluble one, it is a kind of digestion. 

2. The sugar ordinarily used for culinary purposes is 
cane sugar. Its formula is C12H22O11. Explain 
how cane sugar differs from starch chemically. 

Experiment 2 2 . — To demonstrate a test for the presence 
of grape sugar (C6H12O6). 

3. The reagent commonly used for this test is called 
Fehling's solution, from the name of the scientist 
who first employed it. The solution is prepared 
by mixing one volume of each of the following stock 
solutions with two volumes of distilled water (e.g., 
10 c.c. of each, and 20 c.c. of distilled water). 

(i) 17.5 grams of copper sulphate dissolved in 500 
c.c. of distilled water. 

(2) 86.5 grams of sodium-potassium- tartrate (Ro- 
chelle salts) in 500 c.c. of distilled water. 

(3) 60 grams of sodium hydrate in 500 c.c. of dis- 
tilled water. 

The mixture, properly made, has a clear blue color. 



^ . OCCURRENCE OF CARBOHYDRATES IN PLANTS 49 

If the Fehling's solution is not freshly prepared, 
it should be tested, before using, by heating a por- 
tion in a test-tube until it boils. If a precipitate 
of red copper oxide does not form the solution is 
good. It is better to make this test even with fresh 
solution. 

4. Place a very small amount of grape sugar into a test- 
tube one-third full of water. 

5. Shake the solution and gently warm it, then add a 
few drops of Fehling's solution. 

6. Describe what results. The effect is due to the 
grape sugar reducing {i.e., taking oxygen from) the 
cupric sulphate in Fehling's solution, forming 
cuprous oxide 

7. State the test for grape sugar. 

Experiment 23. — To demonstrate a test for the pres- 
ence of cane sugar. 

8. Proceed as in the preceding experiment, using cane 
sugar instead of grape sugar. Observe and describe 
the result. 

9. Prepare a second test-tube with a solution of cane 
sugar. 

10. Add several drops of hydrochloric acid, and boil the 
mixture. 

1 1 . Now add several drops of Fehling's solution (enough 
to neutralize the acid). 

12. State the test for cane sugar. 

Experiment 24. — -To demonstrate the occurrence of 
sugar in plant tissues. 

13. Test portions of onion, beet, sweet corn, sweet 
potato, etc., for sugar. Describe the result in each 
case. 

14. Write a brief summary of what you have learned 



50 ANATOMY AND PHYSIOLOGY 

concerning the occurrence and distribution of carbo- 
hydrates in plants. 
C. Tests for Cellulose: 

1. Mount a few threads of cotton (cotton wool) in 
water under a cover glass. Cotton fibers are com- 
posed largely of cellulose. Irrigate under the cover 
glass Ts-ith a Kttle dilute sulphuric acid, and follow 
the acid ^"ith the iodine solution. Draw the various 
liquids under and away from the cover glass with 
a small piece of blotter or filter paper. Observe 
changes throughout under the microscope. 

Observe and record the color of the cotton fibers 
after treatment \^ith iodine. 

2. In a similar manner observe the color change when 
freshly mounted cotton fibers are irrigated vriih a 
solution of Chlor-iodide of zinc. 

3. ]Mount thin sections of various portions of plant 
tissue, such as herbaceous stems, or bits of leaf epi- 
dermis, a few threads of Spirogyra, or plant hairs 
such as are readily obtained from leaves of mullein or 
squash, and apply the above tests. Of what sub- 
stance are the un transformed cell- walls of plants 
composed? 



XI. Formation of Carbohydrates 

A . The Conditions Necessary for Carbohydrate Formation: 
Experiment 25. — To ascertain if light is necessary for 

carbohydrate formation. 

1. A green leaf, previously partly shaded by having a 
strip of black cloth closely affixed to both sides, is 
to be tested for starch as described under Experi- 
ment 21, after having been in the sunlight for several 
hours. Record as previously directed.* 

Experiment 26. — Is chlorophyll necessary for carbo- 
hydrate formation? 

2. As directed under Experiment 21, test a variegated 
leaf, having white areas devoid of chlorophyll. 
Make three drawings of the leaf, as follows: {a) 
showing (by shading) the distribution of chloro- 
phyll in tissues; (5) showing the leaf decolorized; 
{c) showing (by shading) the areas that gave the 
starch reaction with iodine. 

B. Effects of Light on Chlorophyll: 

Experiment 27. — To show the need of sunlight for the 
formation of chlorophyll by chloroplasts. 

1. Examine a seedling of any convenient plant that 
has been allowed to develop in darkness. Compare 
its color with that of another seedling of the same 
species grown in daylight. 

2. Now place the seedling in diffuse sunlight for 
twenty-four to forty-eight hours. Record the re- 
sult, and state your inferences. 

*The "light screen," devised by Professor Ganong, for experiments in 
starch formation by leaves, is specially recommended for this experiment. 

51 



52 ANATOMY AND PHYSIOLOGY 

C. The Exchange of Gases in Photosynthesis: 

Experiment 28. — To demonstrate the evolution of gas 
in photos}Tithesis. 

1. Observe uninjured branches of Elodea growing in 
water in direct sunlight. (For individual experi- 
ments one or two branches in a large test-tube of 
tap- water will serve.) Describe what you observe, 
coming from the basal ends, or other parts of the 
stems. 

2. Shade the plants for a moment by interposing a 
note-book or other convenient screen between them 
and the sun. Describe how the process just ob- 
served is affected. 

3. Make a diagram of the apparatus and material, 
showing what you have observed. 

4. Obser\-e the bubbles among a mass of any green 
alga floating in water, and explain their presence. 

Experiment 29, — To demonstrate what gas is given off 
in photos}Tithesis. 

5. With a rubber band, or other convenient means, 
fasten together (not too tightly) the cut ends of 10 
or 15 clean branches of Elodea^ and place them into 
a glass funnel, with the cut ends extending upward. 
Invert the funnel into a jar of water. The surface 
of the water should rise an inch or two above the 
neck of the funnel. 

6. Fill a test-tube with water and invert it over the 
[neck of the funnel, being careful that no air enters 

the tube. 

7. Place the apparatus in bright sunlight, and when 
sufficient gas has been collected in the test-tube, 
test it "wdth a glomng splinter. How is the splinter 
affected by the gas? What gas does this test indi- 
cate? The best success of this experiment requires 



FORMATION OF CARBOHYDRATES 53 

that the gas be tested the same day that the experi- 
ment is set up. Especially avoid setting up the ex- 
periment in the afternoon and testing the gas on the 
following morning. Why? 
Experiment 30. — To demonstrate what gas is taken 
into the plant in photosynthesis. 

8. Into each of three large glass evaporating dishes, 
A, B, and C, place a glass bell-jar having a wide, 
open tubulature at the top. Into two of the bell- 
jars, A and B, place vigorous, green-leaved shoots. 
Into C place no shoot. Under each bell-jar place 
a piece of lighted candle, 2-3 in. high, supported 
on a fiat cork. Now pour water into the evap- 
orating dishes until it rises 2 or 3 in. up the side 
of the bell-jars. The burning of the candles shows 
that there is enough oxygen in the jars to support 
combustion. 

9. Now cork the bell- jars air-tight with rubber stop- 
pers. What soon results to the candle flames? 
What does this tell you of the amount of oxygen 
now in the jars? 

10. Cover the jar B, containing a shoot, with opaque, 
black cloth, and set all three preparations in sun- 
light. 

11. State, in a well- worded paragraph, the condition in 
each bell-jar as to light, chlorophyll, and the com- 
position of the air. 

12. At the end of two or three hours, carefully lower 
into each jar, successively, a lighted candle attached 
to the end of a long wire. Record your observation 
and inference for each jar, and your final inference 
as to what gas is taken into the plant in photosyn- 
thesis, and what conditions are necessary to the 
process. 



XII. The Digestion op Starch: Translocation 



A. The Starch-content of Leaves During the Day and at 
Night:^ 

Experiment 31. — To find out if starch is present in 
leaves gathered in darkness as weU as in light. 

1. DechlorophyUized leaves of clover (or of one of the 
first five plants listed in the table in the foot-note 
below), collected {a) in bright sunlight, (h) several 
hours after sunset, will be tested by the instructor 
for the presence of starch. 

2. Did both leaves probabty contain starch during 
the day? From this experiment what do you 
know has taken place in the leaf gathered at night? 
Is starch soluble? What, then, must have occurred 
to the starch? 

^Miss EcEERSON {Bot. Gas., 48: 224-228. S1909) recommends the 
following plants for this study, siace in them photosjmthesis is verj^ ac- 
tive, starch disappears from their l^,ves in darkness mth comparative 
rapidit3% chlorophj^ll is easil}'' extracted, and the iodine reacts quickly: 



Name of Plant 


Disappear- 
ance of starch 
1 in darkness 
i;(T. i8°-22"C.) 

! 


Fonnation of 
Hght (T. 20" 


staroh in 
-25X.) 


Tndrne 


Perceptible 
fig. 


Good fig. 


test 




Xights 


da5-s 


Minutes 


Minutes 


JSIinutes 


Cucurbita Pepo. . . . 







15 


50 


4-15 


Heliantkus annuus. 







30 


120 


5 


Impatiens Sidtani. . 







30 


120 


S 


Pkaseolus vulgaris. . 







20 


90 


5 


Ricinus communis 


I 





20 


60 


5-15 


TroP(Bolum majus. . 


2 


I 


50 


90 


I 


Zea Mays 


3 


2 


30 


120 


5 



54 




THE DIGESTION OF STARCH 55 

3. Name two advantages to the plant of this new 
process you have studied. 

4. The changing of an insoluble substance to a soluble 
one and dissolving it is digestion. 

5. Briefly enumerate, in order, using the proper 
scientific terms, the processes that you have learned 
take place in a green leaf from sunrise to sunrise 
again. 

B. Conversion of Starch to Sugar: 
Experiment 32. — To see if starch may be digested 

to sugar by an enzyme. 

1. Into a test-tube one-half full of a dilute starch 
mixture place several drops of iodine. 

2. Add to this mixture a few drops of a solution of 
diastase. 

3. At intervals of fifteen to twenty minutes test for 
sugar. Describe all color changes observed through- 
out the experiment. 

C. State with special care and detail the inferences warranted 

by experiments 31 and 32.^ 

1 Note: The study of proteins and fats is here omitted, not being con- 
sidered essential in an introductory course. 



XIII. -\lc OHOLic Fermzxtation 

A. The dedclopmerU of heat by akoJwlic fermentation: 

1. In these experiments fresh compressed yeast may- 
be used, and, for a fermenting substance, either 
commercial molasses 20 c.c. ' in water (100 ex.), 
or Pasteur's solution, made up as foUows: 

Pasteur's Ftr'':^::::ioH Solution 

Grape sugar 15c c.c. 

Ammonium tartrate 10 c.c. 

Magnesium sulphate 2 grams 

Calcium phosphate 2 grams 

Potassium phosphate 2 grams 

Distilled water S3S c.c. 

Experiment 33 . — To ascertain what temperature change 
accompanies alcoholic fermentation. 

2. Place about 5 grams of compressed yeast in 250 
c.c. of the Pasteur's solution, shake weU. and pour 
into a Dewar flask. 

3. Place a similar amount of distiUed Tor tap") water 
in a second flask. 

4. Record the temperatures of both Hquids at once, 
using two thermometers which should remain in 
the liquids until the experiment is over.- The 
experiment wiU work best if the liquids are at 
a temperature of about 25^0. 

^The instructor will, of course, understand the necessity of carefully 
comparing the initial readings of the thermometers, where two or more are 
used, and of making necessary corrections in subsequent readings. 

56 



^. ALCOHOLIC FERMENTATION 57 

5. Set two Dewar flasks side by side where they 
will not be subject to great or unequal changes 
of external temperature. 

6. At frequent intervals {e.g., twenty minutes) during 
the next two hours, record the temperatures of 
the two fluids. Continue the records over as long 
a period as convenient, not exceeding twenty-four 
hours. 

7. Tabulate the results, and from the figures con- 
struct two ''curves," showing the rate and amount 
of temperature change in each flask. 

8. State your inferences from this experiment. 
B. The gaseous exchange in alcoholic fermentation: 

Experiment 34. — To ascertain what gaseous exchange 
accompanies alcoholic fermentation. 

1. Place 250 c.c. of fermenting mixture into a tall 
glass cylinder, and 250 c.c. of distilled water into 
a similar adjacent cylinder, as a control. At 
once test the air in the cylinders above the liquid 
with lime water, to see if the latter turns milky, 
as a result of the formation of a precipitate of 
carbonate of lime.^ 

2. After the test for CO2, test the air in both cylinders 
with a lighted splinter or taper, to see if it contains 
sufficient oxygen to support combustion. The 
taper should be rapidly lowered into and removed 
from the cylinder. Why? 

^ If the members of the class are not familiar with the effect of CO2 on 
lime water, this should be demonstrated by the instructor, using both 
chemically prepared CO2 and the breath from the kings, before proceeding 
with the experiments in fermentation and respiration. 

The air in the cylinder may conveniently be tested by first dipping a 
small wire loop {e.g., 10 mm. in diameter) into lime water. A film of the 
lime water will form across the loop, and may thus be transferred into the 
cylinder. 



58 ANATOMY AND PHYSIOLOGY 

3. Place a greased glass plate over each cylinder, or 
close the cylinders with a rubber stopper, and after 
an interval of about one hour (at a temperature 
of about 25°C.) repeat the tests for O and CO2. 
Test again after two or more hours. 

4. Record and interpret your results, especially dis- 
cussing any circumstances that may have operated 
to affect the progress of the experiment either favor- 
ably or unfavorably. 

C. The Formation of Alcohol Demonstrated: 

Experiment 35. — To test for the presence of alcohol. 

1. After the fermentation in the last experiment has 
proceeded for twenty-four hours, distill about 150 
to 200 c.c. of the fermenting liquid, and redistill the 
first distillate. 

2. Test a portion of the second distillate with aflame 
to see if it will burn. If it will, describe and explain 
the result. 

3. The presence of alcohol may also be tested, in 
either the first or the second distillate, by adding to 
it several drops of a mixture composed of a strong 
aqueous solution of bichromate of potash, to which 
have been added a few drops of sulphuric acid. If 
a green color results, the presence of alcohol is 
indicated. 

4. Briefly summarize the products of alcoholic fer- 
mentation, ascertained by the above experiments. 
From where did these products come, and what 
was the active agent in their formation? 



XIV. Respiration 

A. Anaerobic Respiration: 

Experiment 2,^. — To illustrate anaerobic respiration. 

1. Remove the seed-coats from three or four pea seeds 
that have soaked in water over night. 

2. Fill a large glass test-tube with mercury, and 
invert it in a bath of mercury. 

3. Place the pea seeds under the mouth of the inverted 
test-tube, and allow them to float to the top. Use 
every possible precaution to prevent air being car- 
ried up with the peas. Can the presence of air 
be entirely prevented? 

4. Securely fasten the test-tube in the inverted posi- 
tion, with its mouth under the surface of the mer- 
cury in the bath, and during the next twenty-four 
to forty-eight hours observe the formation of 
gas, which replaces the mercury around the seeds. 

5. Now introduce into the test-tube with the pea seeds 
a small piece of potassium hydroxide. If the gas 
given off by the seeds is CO2 it will be absorbed by 
the potassium hydroxide, and the mercury will rise 
in the tube. 

6. Do these seeds respire under strictly anaerobic con- 
ditions? Discuss, in your note-book, all the pros 
and cons, and endeavor to make a clear statement 
of just what this Experiment does and does not 
demonstrate. 

B. Aerobic Respiration: 

Experiment 37. — To demonstrate what exchange of 
gases accompanies the aerobic respiration of a living 
plant. 

59 



6o ANATOMY AND PHYSIOLOGY 

1. Place a vigorous potted plant on a ground-glass 
plate. By the side of it place a watch-glass full of 
lime water, or baryta water; over all place a glass 
bell-jar with a large tubulature at the top. 

2. Make the joint between the bell- jar and the ground- 
glass plate air-tight by means of vaseline. 

3. Test the air in the jar with a lighted taper to be sure 
that it contains enough oxygen to support combus- 
tion. 

4. Insert a rubber stopper into the tubulature so as 
to make it air-tight, and set the plant aside, in a 
dark place. Why? 

5. At the next laboratory period (preferably on the 
following day), and without disturbing the bell- jar, 
observe the color of the Hme water in the watch- 
glass. What does it indicate? 

6. Quickly and cautiously insert a lighted taper Into 
the bell-jar through the tubulature. What results? 
What inference is justified? 

Experiment 38. — To see if all parts of a plant, and non- 
green plants, respire. 

7. Take six cylindrical glass jars, a, b, c, d, e, and /", 
provided with air-tight rubber stoppers. 

8. Into (a) place a quantity of green leaves; into (b) 
green stems of some herb; into (c) young clean 
roots* of some herb; into (d) freshly picked flowers; 
into (e) one or two fresh fleshy fungi; and into (/) 
nothing. Confine the plant material to one side 
of the jars by inserting a vertical partition of coarse 
wire netting. 

9. Test the air m each jar to be sure that it will sup- 
port combustion, then cork the jars air-tight, and 
place them in a convenient place. 

10. At the next laboratory period carefully test the air 




RESPIRATION 6 1 



in each jar with the burning taper. What infer- 
ence may be drawn from the result? 

11. Next, pour into each jar a bit of clear lime water, 
and wash the air by tipping the jars back and forth, 
holding the half containing the plant material upper- 
most. What conclusion does the result justify? 

12. Clearly state the general conclusion from this ex- 
periment. 

C. The Temperature Change Accompanying Plant Res- 
piration: 

Experiment 39. — To ascertain what temperature change 
accompanies the respiration of germinating seeds. 

1. Place a quantity of germinating seeds {e.g., oats, 
wheat, lupine) into a Dewar flask. Into a second 
Dewar flask place nothing. 

2. Into each flask insert a thermometer (being sure 
first to compare their readings). The bulb of the 
thermometer in the flask containing the seeds 
should be well covered by them. Place the flasks 
where they will not be subject to great nor unequal 
changes of external temperature. . 

3. After twenty-four hours record the temperature 
indicated by each thermometer. 

4. Thoughtfully discuss and interpret results ob- 
served. 

5. Compare the process of fermentation with that of 
respiration. What inference is suggested by this 
comparison as to the real nature oi respiration? 



XV. The I^"^LUE^•CE of External Coxditions ox the 

Plant 

^4. Th^ Influence of Gravity an the Direction of Grouth: 
Experiment 40. — To find how gra^-ity affects the direc- 
tion of growth of roots and shoots. 

1. Choose two or three young seedlings of the pumpkin 
or lupine, with radicles about 10 mm. long. 

2. Pin the seedlings horizontally on a cork and place 
in a moist chamber in tlw dark (why in the dark?) 
until the next period. A Petri dish will furnish a 
simple moist chamber. 

3. Make a drawing of the seedlings in the horizontal 
position. 

4. At the next laboratory period observe the position 
of both root and shoot. Draw. 

5. Do the results give any evidence that the root grew 
downward and was not pulled down b}* gra^ity? 
Explain. 

B. Influefice of Light an the Rate of Growth of Stems: 

1. Compare the lengths of the stems of seedlings of the 
same age that have grown, one in the dark, the other 
in the hght. State the exact length of each of the 
stems in centimeters. 

2. What do you infer is the effect of hght on the rate 
of growth of stems of the plants ohserced? 

3. Do you think this is true of all plants? (This point 
should be discussed "^-ith the instructor, in the Hght 
of more recent investigations on the subject. See 
especially. MacDougal. ^'The Efccts of Light and 

62 



INFLUENCE OF EXTERNAL CONDITIONS ON THE PLANT 6^ 

Darkness on Growth and Development.^' Memoirs 
of the New York Botanical Garden, No. 3.) 
C. The Influence of Light on the Direction of Growth of Roots 

and Stems: 

Experiment 41. — To ascertain how one-sided illumina- 
tion affects the direction of growth of roots and 
stems. 

1. Fix a vigorous young seedling of white mustard 
with the root extending through the mesh of a piece 
of cheese-cloth stretched over the mouth of a large 
salt-mouthed bottle nearly filled with tap-water. 
The seedling should be as straight as possible, and 
stand vertically at the beginning of the experiment, 
with root extending well into the water. 

2. Place the plant thus prepared into a box with a 
tightly fitting cover and a narrow, vertical slit at 
one side to admit the light. (A pasteboard shoe- 
box with the cover on, and the slit cut vertically 
in the cover will answer.) 

3. Set the box and plant in a well-lighted window, 
with the slit toward the light. 

4. Make a diagram of the entire apparatus and plant, 
in longitudinal section. 

5. At the next laboratory period carefully remove the 
cover from the box and observe the position of the 
root and stem. 

6. Draw another diagram similar to, and by the side 
of the first one, showing what you observe. 

7. Compare the manner of response of the root and 
stem to one-sided illumination. 



PART II 
MORPHOLOGY AND LIFE HISTORY 



I. Meaning of the Terms 

A. Morphology. — Under Part I we considered various 
physiological processes, the primary result of which was 
to maintain the life of the individual plant. Most of 
those processes were found to be carried on by all 
plants. It is common knowledge, however, that plants 
differ widely from each other in both structure and 
habit of life. In other words, we recognize the fact of 
variation. This means that different plants solve the 
same problems of life in different ways. That phase of 
botany which concerns itself with a comparative study 
of structures, and seeks to interpret the structural value 
of an organ, no matter how it may be disguised, is 
termed the science of form, or morphology. 

B. Life History. — Every plant, in the course of its exist- 
ence, passes through a series of changes, in orderly 
sequence. Like an animal, every plant begins life as 
a single cell, the eggy or the equivalent of an egg; 
the egg (except in some of the lower plants) develops 
into an embryo, and the embryo grows and develops 
into an adult. The adult in turn, produces an egg, 
like the one from which it came, thus completing one 
life cycle and initiating another. These various 
changes constitute the life history of the individual. 

5 65 



66 MORPHOLOGY AND LIFE HISTOEY 

C. Descent. — Just as one of the higher plants, such as a 
maple tree, begins life as a single cell, and becomes 
more and more complex as it matures, so the plant 
kingdom as a whole, presents us with a series of organ- 
isms of gradually increasing complexity from the sim- 
plest one-celled forms to myriad-celled, complex forms. 
This fact suggests that the entire plant kingdom, like 
every individual plant, has had a developmental his- 
tory, the more complex organisms being derived from 
more simple ones by a series of gradual changes. This is 
the theory of descent, or organic evolution. It teaches 
us that all organisms are related to each other, and 
is one explanation of why we so often find the same 
organ appearing again and again, under various guises, 
in plants externally unlike. 

D. Classification. — The study of morphology and life 
histories enables us to recognize relationships among 
plants, and hence to build up a genealogical tree, 
showing lines of descent. Thus we can arrange plants, 
together with their nearest relatives, in groups; and 
related groups, again, in larger groups of successively 
higher orders. This gives us a rational basis for the 
classification of plants, and this phase of plant study 
is called systematic botany, for it makes possible 
the arrangement of plants in a system, which en- 
deavors to show how the plant kingdom, in all its diversity, 
has developed, or evolved. This greatly simplifies our 
study of plants, for the number of different plants is too 
great for us to study every one; but if we recognize 
that each plant more or less imperfectly illustrates 
a group, then we can study an illustration of each 
group, and thus get a more nearly adequate picture 
of the kingdom of plants as a whole. The various 
systematic groups are given in E below. 



'^ MEANING OF THE TERMS 

E. An Outline of the Classification of Plants:^ 
The Great Groups of Plants 



67 



Division 



I Thallophyta.. < 



Subdivision 



A. Algse 



B. Fungi. 



Class 

1. Cyanophyceae 

2. Diatomaceae 

3. Chlorophyceae 

4. Phseophyceae 

5. Rhodophyceae 

1. Myxomycetes 

2. Schizomycetes 

(Bacteria) 

3. Phycomycetes 

4. Ascomycetes 

5. Basidiomycetes 

6. Fungi imperfecti 

(life histories 
imperfectly known) 



Order 



II. Bryophyta. 



I. Hepaticse 



III. Pteridophyta. 



[ I. Sphenophyllineas. . 
IV. Calamophyta s 2. Equisetineae 



Ricciales 
Marchantiales 
J ungermanniales 
Anthocerotales 

Andreales 

2. Musci \ Sphagnales 

Bryales 
Ophioglossales 
Marratiales 
[ Isoetales 

/ Filicales 
1 Marsiliales 

Sphenophyllales 
Equisetales 



I. Eusporangiatae. 



2. Leptosporangiatae 



V. Lepidophyta. 



( 3. Calamarineae Calamarales 

I. Lycopodineae Lycopodiales 

[ 2. Lepidodendrineae. 



/ Selaginellales 
1 Lepidodendrales 



VI. Cycadophyta. 



1. Cycadofilcineae Cycadofilicales 

2. Cycadineae. Cycadales 

3. Bennettitineae Bennettitales 

[ Cordaitales 

4. Cordaitineae I Ginkgoales 

[ Gnetales 



^For reference, not memorizing. 



68 



MORPHOLOGY AND LIFE HISTORY 



The Great Groups oe Plants — {Continued) 



Division . 


Subdivision 


Class 


Order 




A. Gymno- 
spermse 


I. Pinoideae 


' Coniferales 

. Taxales 
Pandanales 
Naiadales 
Graminales 






I. Monocotyledoneae . . . 


Arales 

Xyridales 

Liliales 

Scitaminales 

Orchidales 






2. Dicotyledoneae. . . . .32 


Orders, including 


Spermatophyta 


B. Angio- 




Salicales 




spermae . 


• 


Polygonales 






(a) Archichlamydeae 


Ranunculales 






Apetalee 


Resales 






Polypetalas 


Violales 

Myrtales 

Umbellales 

Ericales 






(6) Metachlamydeae 


Polemoniales 






Sympetalas ( = 


Plantaginales 






Gamopetalse) 


Rubiales 
^ Campanulales 



i 



2. Directions for Study 
Pol3rpodium vulgare (Common polypody) 

A. Classification: 

Division III. Pteridophyta (fern plants). 
Class I. Leptosporangiatae. 
Order. Filicales. 

Family. Polypodiaceae. 
Genus. Poly podium. 
Species, vulgare L. 

B. Habitat: 

I. Record here your knowledge of the habitat of the 
specimen studied. The information is to be ob- 
tained from your own observation, and from your 
reading and class work. 

The ''Fern Plant" 

C. Naked-eye Characters: 

1. General features. 

(a) Note that the sporophyte is differentiated 
into root and shoot. 

(b) The leaf portion of the shoot is often called the 
frond. The fibrous roots and the leaves are 
borne on an underground stem (rhizome). 

(c) Make a sketch of the entire sporophyte (in- 
cluding only one leaf). 

2. The rhizome. 

(a) Describe the natural attitude (i.e., erect, or 
horizontal) of the rhizome. Where does it 
69 



70 MORPHOLOGY AND LIFE HISTORY 

grow? If it branches, describe its manner 
of branching. 

(b) Does the rhizome bear an}^ outgrowths besides 

the leaves and roots? If so. describe their 
structure, color, relative number, and location. 

(c) The places on the rhizome where the leaves are 
borne are called nodes. What is the region 
between two nodes called? 

Note. — The directions below (d-i) apply especiall}" to 
the bracken fern, Pteris aquilina. 

(d) Observe the end of a rhizome, cut squarely 
across. If preserved material is used, the cut 
surface should be kept moistened during the 
study. The obser\^ations may best be made 
from a piece .5 to 10 mm. thick, cut transversely 
and placed in a watch-glass of water. Do not 
cut or injure 5^our specimen in any way, as it 
will be collected for further preservation at the 
end of the study. 

(e) Distinguish the following tissue-regions: 

(i) The epidermis (black inpreser\'ed material). 

(2) Underneath the epidermis a narrow, dark- 
colored region of h5rpodermal sclerenchyma. 

(3) Within the h^-podermal sclerenchyma the 
fundamental tissue fparenchjmia^ 

(4) Imbedded in the parenchyma two promi- 
nent elongate, dark-colored areas, the central 
sclerenchyma, or stereome (sometimes fused 
into one). 

(5) Also imbedded in the parenchyma, and sur- 
rounding the iimer sclerenchyma, several 
areas of fibro-vascular bundles. In fresh 
specmiens these areas are yello^\"ish, in 
preserved material they are lighter colored 



POLYPODIUM VULGARE J I 

than the inner sclerenchyma. How do 
they appear when a section is held to the 
Hght? 

(/) Identify all the areas referred to above (e, 1-5) 
in a longitudinal section of the rhizome. 

(g) At home, write a well-worded description of 
your observations under e and /. 

(h) Make a diagram, 10 cm. in longest diameter, 
showing carefully the outline of the rhizome as 
seen in cross-section, and all the tissue-regions 
identified. Label each region, and underneath 
your drawing indicate the amount of enlarge- 
ment. 

(i) Underneath the first diagram make a second 
one, of the same enlargement, showing the rela- 
tion of the tissues of the rhizome as seen in 
longitudinal section. 

The roots. 

(a) Describe the location, form, length, diameter, 
branching, relative number, and relation to 
each other (i.e., close together or not; inter- 
woven or not) of the roots. Draw. 

The leaves. 

(a) On what surface of the rhizome are the leaves 
borne? 

(b) Note their differentiation into stem-like part, 
the petiole, and expanded portion, the blade. 

(c) What is the color of the leaf? Describe and 
suggest a probable reason for any differences in 
color. 

(d) Is the petiole glabrous (smooth, without hairs), 
or pubescent (hairy) ? 

(e) Is the blade entire, or divided into pinnae? If 
the latter, do the clefts between the pinnae ex- 



72 MORPHOLOGY AXD LITE HISTORY - 

tend clear to the midrib? Compare the basal 
with the more distal clefts in this respect. 
(/) Do the pinnae appear to be all of the same age? 
If notj state reasons for considering some of 
them younger than others. Find e\-idence in 
your specimen of the method of formation of 
the pinnae. Are they opposite or alternate? 

{£) Describe and compare the venation of the blade, 
and of the indi\idual pinnae. Describe any 
constant relationship between the venation and 
manner of branching of the blade. 

(/j) Do the smaller veins anastomose (i.e., have their 
ends united so as to form a network), or are 
their ends free? Compare the fern leaf in this 
respect with the foliage-leaf of a seed-bearing 
plant. 

(i) Describe the appearance of very young, unex- 
panded leaves or portions of leaves. 

(^) On the ventral surface of some of the leaves find 
the brownish fruit-dots, or sori (sing, sorus). 
Describe their location. Do you find them on 
the midrib of the frond or on the indi\'idual 
pinnae? Are they between the smaller veins or 
on them? If the latter, on what part of the 
vein? Is their position constant {j.e., always 
the same) ? Are they located at the margin of 
the frond or pinna, or back from the margin? 
Describe their shape. 

(/) Do the sori occur on all the pinnae of a leaf? 
On all the leaves? Compare several specimens 
with reference to this point. 

(w) Observe, using hand lens if necessary, that the 
sorus is composed of a group of small organs 
(sporangia). What do sporangia produce? 



^ POLYPODIUM VULGARE 73 

(n) Is there a membranous expansion (indusimn) 
covering the sporangia in your specimen? Ex- 
amine fronds of the other species of fern dis- 
played in the laboratory and record your obser- 
vations on this point, stating the names of the 
species observed. 

(o) Leaves bearing spores are sporophylls. Fern 
leaves that do not bear spores are vegetative 
leaves or foliage-leaves. 
(p) Do some of the sporophylls also function as 
foliage-leaves? 

(q) Examine specimens of other kinds of ferns ex- 
hibited in the laboratory and see if your answer 
to (p) is true of all ferns. Describe briefly any 
exceptions found, giving the name of the fern. 

(r) Make drawings, natural size, illustrating all 
features of the frond not clearly shown in your 
first sketch. 
D. Microscopic Characters: 
I. The rhizome. 

(a) Study prepared slides of cross-sections of the 
rhizome. {Pteris aquilina is suggested as spe- 
cially satisfactory for this study, a-g.) 

(b) With the low power survey the section and 
identify the various tissue-regions already dis- 
tinguished. 

(c) With the high power, study the epidermis, and 
describe how many cells it is in thickness, the 
variation in thickness of the cell-walls, the 
middle lamella, separating the adjacent cells, 
and the canals, or channels, extending from the 
cell-cavity outward through the cell-wall. Do 
these canals ever branch? Do they form a 



74 MORPHOLOGY AXD LITE HISTORY 

network? Is there any connection between 
the cell-ca\'ities of adjacent cells? 

(d) In a similar manner examine the cellular struc- 
ture of the h^-podermal sclerenchyma. 

(e) Make drawings illustrating the features ob- 
served in (c) and (d), showing four cells of the 
epidermis, and three or four of the underh*ing 
sclerenchyma-cells. The cells should not be 
less than lo to 15 mm. in diameter. 

(/) Make similar studies and drawings of the cells 

of the parench\Tna. 
(g) Study one of the smaller fibro-vascular bundles 

and distinguish, from the circumference toward 

the center: 

(i) The outer bundle-sheath, or endodermis. 

(2) Within the endodermis, and adjacent to it. 
a single layer of starch-bearing parenchy- 
matous cells, the phloem-sheath. 

(3) Thick- walled bast-fibers. 

(4) Larger,' thin-walled cells, ha\'ing their cell- 
walls perforated, the sieve-tubes. 

(5) Associated with the cells mentioned in 
(2)-(4), parench\Tna-cells (phloem-paren- 
chyma), containing starch. 

(6) The cells mentioned in (3)-(5) constitute 
the phloem-region, of the bundle, or 
phloem. 

(7) Within the phloem is the xylem-region. or 
xylem, composed of 

(8) Large, conspicuous tracheids, whose walls 
have ladder-Hke (scalariform) markings, as 
seen in longitudinal section. Each tra- 
cheid is formed from a single, elongate, 
tapering cell; the li\'ing matter, or proto- 



POLYPODIUM VULGARE 75 

plasm, has disappeared, leaving only the 
cell-walls, unevenly thickened. In some 
plants {e.g., the pine) the thickenings form 
''bordered pits." 
(9) Smaller sieve-tubes, resembling those of 
the phloem. 

(10) Thin-walled cells forming the wood-, or 
xylem-parenchyma. 

(11) Since the tissues of the fibro-vascular 
bundles are arranged circularly about a 
common center, the bundle is called a 
concentric bundle. 

(12) Compare the various bundles and see if 
they are all of similar structure. 

(13) Make a careful drawing showing the 
structure of the bundle, including all points 
mentioned under (g), (i)-(io). This draw- 
ing should be at least 75 mm. in longest 
diameter. 

2. The pinna. 

(a) Under the low power examine a small portion of 
one of the pinnae or pinnules not bearing a 
sorus, and note the presence or absence of 
outgrowths. 

(b) Can you observe any veins too small to be seen 
with the naked eye? If so, describe their re- 
lation to each other. 

(c) Mount a small bit of the lower epidermis, and 
describe (a) any outgrowths; (b) the stomata 
and guard-cells, stating the number, shape, 
and contents of the latter. Describe the rela- 
tive number and distribution of the stomata. 

(d) Compare the stomata of the fern with those of 
a seed-bearing plant. 



76 MORPHOLOGY AKD LITE HISTORY 

(e) Make dra'vs^ngs shoeing all features shown 
under 2, {b)-{d). 

(/) Describe a cross-section of a pinna as shown in 
a prepared slide. Draw. Compare its struc- 
ture with that of a foKage-leaf of a higher plant. 
E. Non-sexual Reproduction: 

1. Describe the possibilities of vegetative propagation 
of the sporophyte. 

2. With a needle remove several sporangia from a 
sorus, mount them in water and study under low 
power. 

3. Observe the differentiation of the sporangium into 
a stalk (pedicel), and a spore-case, containing 
spores. Note the walls of the spore-case, and the 
row of thickened cells, the anntilus. Describe these 
cells. Note the special place for opening of the 
spore-case, through which the spores escape between 
the lip-cells. 

4. Make a drawing of the sporangium, about ^^ mm. 
in shortest diameter, showing a portion of the 
pedicel. 

5. Study the shape and surface markings, if any, of 
a single spore. Account for the shape. Are they 
all of substantially the same size, i.e., is Poly podium 
a homosporous pteridophyte? 

6. Make a drawing of the spore 15 mm. in longest 
measure. 

7. Run a drop of glycerine under the cover-glass and 
carefully watch for the snapping motion of the 
sporangia by which, in nature, the spores are 

• expelled. 

8. Explain the advantage to the species of ha\'ing the 
spores expelled. Why would it not be as well if 
they merely dropped out of the spore-case? 



% POLYPODIUM VULGARE 77 

9. If suitable material is at hand, study stages in the 
germination of the spores, and draw. 

10. To which of the alternating generations does the 
fern-plant belong? Why? 

11. Into what does the spore develop? 

The Prothallus 

F. Habitat: 

I. State the locations and conditions of growth of the 
prothallus (also called prothaUium) , (a) in artificial 
culture; (b) in nature. 

G. Naked-eye Characters: 

1. Describe the exact size (in millimeters); color, and 
shape of the prothallus. 

2. Is it differentiated into a dorsal and a ventral sur- 
face? If so, how are the two surfaces distinguished? 

3. Describe the location and character of the rhizoids. 
H. Microscopic Characters: 

1. Mount a prothallus in water or clearing fluid, ven- 
tral side up, under a cover-glass. 

2. Describe the structure and contents of the cells. 

3. Describe variations in thickness. Do you find a 
thicker central portion, or cushion? 

4. Observe the growing point in the notch. 

5. Study the location and character of the rhizoids 
Are cross- walls present? 

/. Sexual Reproduction: 

1. Among the rhizoids find small elevations, the 
antheridia. Describe their number and distribu- 
tion. 

2. Nearer the notch observe the archegonia, appearing, 
in cross-section, to be composed of four cells, sur- 
rounding an opening or canal. 

3. Make a drawing, at least 5 cm. in longest diameter, 



78 MORPHOLOGY AXD LIFE HISTORY 

showing all features of the prothallus thus far 
observed. By the side of this figure draw an out- 
line of the prothallus, natural size. 

4. In fresh specimens motile antherizoids or sperms 
may be found escaping from the antheridia and 
swimming in the water. If these are found, observe 
the body -of the sperm and the cilia. How many 
cilia are there? Draw. 

5. If prepared sHdes are suppHed, study cross-sections 
of the prothaUium passing through an antheridium 
and an archegonium. Describe accurately, noting 
the differentiation of the archegonium into a neck, 
containing a neck-canal, and a venter, containing 
an oosphere or egg. 

6. Make a diagram of the section, of the same scale 
as the drawing in 3 above, and make drawings 
showing details of structure of the antheridia and 
archegonia as seen in longitudinal section. 

7. To what class of reproductive bodies do the sperm 
and egg of the fern belong? To which of the alter- 
nating generations does the prothallus belong? 
Why? Why is it called a thallus? 

8. Is this f ern moncecious or dicEcious? Explain. 

9. What structure is the starting point of the sporo- 
phyte? 

10. Diagram the life history of the fern for three genera- 
tions, by continuing the following diagram; letting 
G = gametophyte; s = sperm ;e = egg;S = sporo- 
phyte ; sp = asexual spore : 

G<' y>S-?, etc. 

11. Make a diagram to show the life cycle of the fern, 
using arrows and words, arranged in a circle. 



POLYPODIUM VULGARE 



79 



K. Nutrition and Growth: 

1. Is photosynthesis carried on by both gametophyte 
and sporphyte? Transpiration? Absorption of 
water frorn the soil? 

2 . Explain the need of stomata in the sporophyte. Are 
they present in the gametophyte? Explain. 

3. Discuss the presence or absence of a conducting 
system in the prothallium and sporophyte. 

4. Explain how the presence of the cushion of the pro- 
thallium is related to the needs of the young sporo- 
phyte. 

5. Is the gametophyte oi Poly podium ever dependent 
upon the sporophyte for its nutrition? Its exist- 
ence? 

L. Comparison of Gametophyte and Sporophyte of Poly- 
podium: 
Copy the following table into your note-book, and mark 

X after the word gametophyte or sporophyte in the 

proper column. 









Table I 


























J. QJ 







1 M 


1 03 


1 1 m 




















<U (U 




ca c 






w 








"2 c 


'-(J 


to 


^•-3 


'd 


« ft-2 


















rt 


,-. 


3- 


60 0;+^ 






<u 








!/i 


ClJ 




ai.a 


0) t. 




c 


^ 








•M'S 


u 


cS 


3 


> G 













•M 


^^ 




U 




OT > 


3 


Generation 


2 
S, 

m 


>> 

S 


Ah 


S 


CO 


'0 




u 

pi 

U 


(U+J 

a'2 
a 




^ 

"o 
X 

^ 


W43 



to 3 

" n, 

•" 2 

pq ft 




*" S 
m ft 


Has bot 
tive an 
ductive 


Gametophyte 
























Sporophyte 

























Polytrichum commime (Common hair-cap moss)V 

A. Classification: 

Division II. Bryophyta (moss-plants). 
Class II. Musci (mosses). 
Order. Bryales. 

Family. Polytrichaceae. 
Genus. Polytrichum. 
Species, commune L. 

B. Habitat: 

I . Polytrichum commune is widely distributed, growing 
in the soil in fields and woods. 

C. Naked-eye Characters: 

The Gametophyte (The ''Moss-plant") 

1. Note that there are two kinds of leafy ''moss- 
• plants." The one having the cup-like tip is the 

male or antheridial plant; the other, without the 
cup-like tip, is the female, or archegonial plant. 
Compare the average height of the mature male 
and female plants. Do you find any outgrowth 
from the tip of any of the archegonial plants? 

2. Are the moss-plants differentiated into root and 
shoot? Is the shoot further differentiated? If 
so, describe. 

3. Briefly describe the extent and ramifications of the 
''root" system. Are these true roots, with root- 
hairs ? 

4. Briefly describe the arrangement of the leaves on 

1 With minor modifications the outline here given for the study of the 
moss will serve for species of Mnium, Funaria, or almost any other com- 
mon moss. 

80 



POLYTRICHUM COMMUNE 8 1 

the stem (opposite, alternate, spiral). Are the 
leaves sessile or petiolate? Simple or compound? 
Is there a midrib? Veins? Compare the dorsal 
and ventral surfaces of the leaves. Describe 
any variations in the leaves on various parts of 
the stem. Describe the margin of the leaf -blade 
(i.e., entire, notched, serrate, etc.), and the shape of 
its apex and base. 

5. Compare the form of the leaves in the same regions 
of the male and female plants. Note especially 
the rosette of perichaetae (modified leaves) at the 
summit of the male plant. Compare them with 
the foliage-leaves below them. 

6. Describe the form of the stem. Is it of uniform 
diameter? Does it branch? Compare the stems 
of the male and female plants. 

7. Make suitable drawings, illustrating all points 
observed under C 1-6. 

The Sporophyte 

8. Select an archegonial plant with sporophyte (sporo- 
goniimi) attached. Distinguish the long stalk 
or seta, bearing at its summit the spore-case, or 
sporangium. How many millimeters long is the 
seta ? Describe its surface ; its diameter throughout ; 
its shape in imaginary cross-section. If it is angled, 
how many angles are there? By taking hold of 
the seta near its attachment to the gametophyte 
and carefully pulling, separate the sporogonium 
from the gametophyte. State, with full reasons, 
whether or not the tissue of the foot appears to be 
continuous with that of the gametophyte. Does 
anything like grafting of the sporophyte onto the 
gametophyte take place? 



82 MORPHOLOGY AKD LIFE HISTORY 

9. Do you find a swelling of the seta ("apophysis), 
just beneath the sporangium? If so, describe and 
locate it accurately. Do its cells contain chloro- 
phyll ? Of what function is, or is not, the apophysis 
therefore capable? 

10. Remove and study the cap fcalj'ptra) that fits 
over the sporangium. Describe its shape, margin, 
character of surface, outgrowths, if any. 

11. Study the color, shape, and other features of the 
sporangium disclosed by remo\dng the cah^tra. 
Measure its length and breadth. Describe its 
attitude on the seta (i.e., erect, pendant, etc). De- 
scribe its outHne in imaginary cross-section. If 
it is angled, record the number of angles. 

12. Describe the shape and surface of the Hd (oper- 
culum) at the end of the sporangium, and just under 
the cal>^tra. 

13. Make a drawing, ten times natural size, showing 
the sporangium, the cah^tra removed, and a por- 
tion of the seta. 

14. Carefully remove the operculum and preserve it. 
On the margin of the sporangium, underneath the 
operculum, observe the circle of teeth-like organs 
(peristomeV Record the number of teeth. Is 
this number constant? Is it always either even 
or odd?" Draw. 

15. In fresh dry specimens describe the effect of the 
breath upon the position of the teeth of the peri- 
stome. 

16. Describe the membrane (epiphragm) within the 
peristome, and covering the end of the capsule. 
Is it perforated? What is its relation to the teeth 
of the peristome? 

17. Make a drawing, 30 mm. in diameter, illustrating 




POLYTRICHUM COMMUNE 83 

an end view of the sporangium with the operculum 
removed. Make a drawing of the operculum, 
also 30 mm. in diameter. 

18. With the razor carefully make a longitudinal section 
of the capsule, just to one side of its central axis. 
Observe the wall of the sporangium; a central 
organ (columella); and, between the two, a mass 
of spores. 

19. Describe the structural relation of the columella 
to the epiphragm. What, in reality, is the latter? 

20. Describe the relative number, color and attach- 
ment or non-attachment of the spores, so far as 
may be ascertained without the aid of the micro- 
scope. 

21. Make a drawing, ten times natural size, illustrating 
everything observed under 18-20. 

22. From the above observations construct a diagram of 
an imaginary cross-section of the sporangium near 
the middle. Compare the diagram with an actual 
cross-section. 

23. Carefully preserve the sporophyte in a covered 
watch-glass or other convenient moist (not wet) 
place until the next laboratory period, or proceed at 
once with the following observations (D) : 

D. Microscopic Characters: 

The Sporophyte 

1. With a sharp scalpel remove a thin piece from the 
base of the sporangium, cutting parallel to the sur- 
face, and mount it in water with the outer surface 
uppermost. 

2. Examine the mounted tissue under the low, then 
under the high power, to see if stomata are present. 



84 MORPHOLOGY AND LITE HISTORY 

If they are, describe them and their distribution. 
Compare them with the stomata of a foliage-leaf 
of one of the higher plants, including the number, 
shape, and other characters of the guard-cells. In 
like manner compare them with the stomata of the 
fern. State, mth reasons, which t5^e of stomata 
you consider the more primitive. Look for stomata 
on the surface of the apophysis. 

3. Study thin cross-sections of the sporangium (sec- 
tions of the haK (C, 18) -v^ill serve). Identify the 
parts already studied, and their characters and 
relationship as seen in cross-section. Make your 
drawings at least 20 mm. in radius. 

4. Describe the shape of the spores, and their manner 
of attachment or non-attachment, as seen under 
high power. Of how many cells is one spore com- 
posed? Make a draT\dng of three spores making 
each 10 mm. in longest measure. 

5. Mount thin cross-sections of the seta, and study 
under high power. 

6. Distinguish the outer layer, epidermis. How 
many cells thick is it ? Observe the central strand, 
and between this and the epidermis a thin-walled 
tissue (parench5mia), and a layer of thicker walled 
cells (sclerenchyma). State how these various 
tissues may be distinguished from each other. Of 
what value is the sclerenchyma? The central 
strand is comparable -v^dth the fibro-vascular bundle 
of the seed-bearing plants. Draw. 

The Gametophyte 
The Leaf. 

7. Remove an entire leaf and mount it in water. Ob- 
serve under low, then under high power. 




POLYTRICHUM COMMUNE 85 

8. How many cells thick is it? Is it of uniform thick- 
ness? Describe. Are stomata present? Why? 
How is the midrib distinguished? Describe the 
leaf-margin and apex. Describe any differences 
in the two sides of the leaf. 

9. Describe fully the contents of a single cell, as 
observed under high power. 

10. Illustrate by suitable drawings all features observed 
under D, 7-9. 

The Stem. 

11. Study, under the low power, cross-sections of the 
stem mounted in clearing fluid (or use prepared 
slides) . 

12. Describe the tissues observed, and their relation to 
each otter. Compare the structure of the game- 
tophyte-stem, as seen in cross-section, with that of 
the sporophyte-stem, and name the tissues of the 
former, using the terms given above {D, 6). 

E. N on- sexual Reproduction: 

1. In some mosses a second gametophyte often devel- 
ops from the tip of an older plant. This is called 
proliferation. Frequently this may be repeated a 
number of times, forming a chain of plants, each 
younger one growing out of the apex of the next 
older one. Examine the material at hand, and, if 
such a condition is found, describe it, with drawing. 
What kind of reproduction is this? 

2. Explain the advantage to the species of the elon- 
gation of the seta. 

3. If stages in the germination of the spores are avail- 
able, study this process. The structure imme- 
diately developed from the spore is the protonema. 
Describe its color. Is it simple or branched? Are 
cross- walls present? 



86 MORPHOLOGY AND LITE HISTORY 

4. At certain points on the protonema observe buds. 
These buds develop into either male or female 
gametophytes (gametophores). 

5. Which generation of the moss-plant always devel- 
ops from the spores? Compare this with the case in 
the fern. 

F. Sexual Reproduction: 

The antheridia 

1. Take a male gametophyte and, with a dissecting 
needle, carefully remove some of the antheridia 
borne in the rosette at the summit of the plant. 
Mount them in water, and study them under the 
microscope. 

2. Describe the shape and othef structural features 
of the antheridia. What is their color? Compare 
them with the antheridia of the fern. 

Do you find paraphyses associated with the anther- 
idia? If so, describe them, and state how they 
may be distinguished from the antheridia. 

4. If prepared slides are available, study longitudinal 
sections through the tip of the male gametophyte, 
observing the mode of attachment of the antheridia. 

5. With high power sturdy the sperms (spermatozoids) 
within the antheridia. 

6. In fresh specimens the sperms may be seen swim- 
ming about in the water. If motile sperms are 
present, endeavor to make out the number and 
character of their organs of locomotion (cilia). Do 
the cilia precede or follow as the sperm moves for- 
ward? Do the motions of the sperm appear to be 
purposeful or not? Give reasons for your answer. 

7. Make drawings showing all features observed under 



POLYTRICHUM COMMUNE 87 

F, 1-6. The antheridia should be at least 25 mm. 
long; the body of the sperms 10 mm. long. 

The archegonia 

8. With the female gametophyte make studies as 
directed above {F, 1-4). 

9. In the archegonium distinguish the venter, neck, 
and neck-canal-cells. Is the archegonium sessile 
or stalked? 

10. If prepared slides are available, identify the 
oosphere, or egg, and, in mature stages, the neck- 
canal. How many cells thick is the wall of the 
archegonium? Is this uniform? What has become 
of the neck-canal-cells? 

11. Make a drawing, at least ;3 5 mm. long, showing all 
features observed under F, 8-10. 

12. Describe the conditions, processes, and organs in- 
volved in sexual reproduction in the moss. Explain 
whether or not it is of advantage to the moss-plants 
that they grow so close together. 

13. Into what does the fertilized egg develop? Where 
does it develop? 

G. Nutrition and Growth:'^ 

The gametophyte 

1. Is the gametophyte of the moss capable of elabor- 
ating its own carbohydrate food? Explain. Is it 
dependent upon the sporophyte at any period of its 
existence? Explain. 

2. How does the possession of leaves affect the surface- 

^ This may be assigned for home work and serve as the basis of class 
discussion, or of written work to be handed in. 



88 MORPHOLOGY AND LIFE HISTORY 

area of the* chlorophyll-bearing tissues? Explain 
how this affects the process of photos}Ti thesis. 

3. State the organs and processes by which water and 
inorganic salts are taken in by the gametophyte. 

4. Explain the presence or absence of stomata in this 
plant. 

5. By what organs is the respiration of the gameto- 
phyte carried on? 

6. Does the gametophyte have to elaborate food in ex- 
cess of its own needs? Explain. Explain the need 
or lack of need of conducting tissues in the gameto- 
phyte. 

7. Name two ways in which the gametophyte is kept 
rigid and erect. 

The sporophyte 

8. Can the sporophyte lead an independent existence 
at any time in its history? Explain. 

9. By what organ or organs, by what process, and from 
what source are water and dissolved food substances 
taken into the sporophyte? 

10. Is photos\Ti thesis possible in the sporophyte at any 
period of its existence? What is the source of its 
carbohydrate food? 

11. Explain the need or lack of need of conducting tis- 
sues in the sporophyte. Compare the degree of 
development of these tissues in the sporophyte and 
gametophyte of the moss. 

12. Explain the significance of the presence or absence 
of stomata in the sporophyte. 

13. Refer to the question mF, 13, and explain the origin 
of the cah-ptra. To which generation does it be- 
long? Explain. 



^. POLYTRICHUM COMMUNE 89 

14. Explain the advantage of sclerenchymatous tissue 
in the sporophyte. Describe the distribution of 
this tissue in the seta, and explain whether or not 
this is an added advantage. 

15. After the sporophyte of Polytrichum begins to de- 
velop, does it grow continuously until maturity, or 
does a period of prolonged rest intervene? Is the 
same true with the sporophyte of the fern? 

16. As directed in /, 10, p. 78, diagram the life history 
of the moss. 

17. Outline the life cycle of the moss, as described in 
7, II, p. 78. 

H. Comparisons: 

1. Write the following names of organs of the gameto- 
phyte of the moss in a column, and opposite them, 
in another column, the names of the corresponding 
organs of the fern; thallus, rhizoid, antheridiophore, 
archegoniophore, antheridia, sperm, archegonium, 
Q^gg, paraphyses. 

2 . In a similar manner compare the organs of the sporo- 
phytes of the two plants, adding the names; sto- 
mata, foot, calyptra, columella, apophysis, sporan- 
gium. 

3 . In a third column make a list of organs of the moss 
not found in the fern; in a fourth column, the organs 
of a fern not found in the moss. 

4. Compare the degree of organization of the gameto- 
phytes of the fern and the moss, as illustrated by 
Poly podium and Polytrichum. 

5. In like manner compare the sporophytes of the two 
classes of plants. 

6. State several reasons for regarding Polytrichum as 
either more or less highly organized than Poly- 
podium. 



Marchantia polymorpha (A Liverwort) 

A. Classification: 

Division II. Bryophyta (moss-plants). 
Class I. Hepaticae (liverworts). 

Order. Marchantiales (marchantia-forms). 
Family. Marchantiaceae. 
Genus. Marchantia. 
Species, polymorpha L. 

The Gametophyte 

B. Habitat: 

I. This plant grows very abundantly on the soil of 
flower pots and benches in nearly all greenhouses. 
In places it becomes a great annoyance to gardeners, 
and is very difficult to get rid of. Out of doors it 
grows in moist, shady places, frequently on rocky 
ledges by streams. 

C. Naked-eye Characters: 

1. Examine first a non-'' fruiting" specimen. 

2. Is the plant-body a thallus? Describe its color, 
outline, and manner of branching. What term is 
applied to this manner of branching? Does the 
plant possess dorso -ventral differentiation? If so, 
how are the dorsal and ventral surfaces distin- 
guished? 

3. Note the texture of the plant, to be ascertained by 
carefully breaking off a piece of fresh thallus. 

4. Describe the appearance of the dorsal surface. The 

90 



MARCHANTIA POLYMORPHA 9 1 

small areas into which it is marked off are areolae. 
Do you find evidence of an air-pore at the center of 
each areola? Is there a midrib? 

5. The cup-shaped structures on the dorsal surface 
are called cupules. Do they occur on definite 
portions of the thallus {i.e., margin, midrib, etc.), 
or irregularly? Describe their color, shape, height, 
diameter, margin. Are they sessile or stalked? 

6. The non-sexual (vegetative) reproductive bodies 
within the cupules are brood-buds, or gemmae 
(sing., gemma). Describe the color, shape and 
size of one (use hand lens) . How are they attached 
to the plant? Do all the cupules contain them? 
Explain your observation on this point. 

7. Examine the ventral surface of the plant. De- 
scribe its color and surface markings, and compare in 
these respects with the dorsal surface. 

8. Note the root-like filaments or rhizoids. Describe 
their shape, color, dimensions, and distribution 
over the ventral surface. 

9. Find purple, leaf -like structures (scales) among the 
rhizoids, and describe their form, position, and 
distribution. 

10. Make careful drawings, showing: 
{a) The plant-body, natural size. 

(b) The surface markings of the dorsal surface, 
enlarged ten times. 

(c) A cupule, side view in perspective, enlarged 
ten times. 

(d) An outline of a gemma enlarged ten times. 

11. Make a diagram of an imaginary cross-section of 
the plant-body, passing through one or more cupules 
(ten times natural size). Label all parts of the 

- drawings. 



92 MORPHOLOGY AND LIFE HISTORY 

D. Microscopic Characters: 

1. The rhizoids. 

(a) With the forceps carefully remove a few of the 
rhizoids and mount them in clearing fluid. 
Examine them first under low, 'then under high 
power. 

Q)) Do you find different kinds of rhizoids? If so, 
how are they distinguished? Are there cross- 
walls? Describe the contents of the rhizoids. 
Do they branch? Explain the shape of their 
tips, and the thickness of their cell- walls. 

2. The gemmae. 

{a) Remove several gemmae with a scalpel, being 
careful not to cut or otherwise injure them, 
and mount them in a drop of water. Examine 
with low power. 

{b) Are the gemmae more than one cell thick? Is 
their thickness uniform? Describe. 

{c) Find on the margin the scar, where the gemma 
was attached to its pedicel, or stalk. 

{d) Find two vegetative notches, i8o° apart. How 
do they differ from the scar? Find papilla-like 
cells in these notches. Do they contain chloro- 
phyll? Do they secrete mucilage? In the 
apex of each of these notches is a vegetative 
point from which a new thallus will develop. 
The mucilage protects it. 

{e) Are there any surface outgrowths? Is there 
dorso-ventral differentiation? Compare them 
in this respect with the thallus to which they 
give rise. So far as you can detect, would it 
make any difference which side up the gemma 
lay when it was sown? 



MARGHANTIA POLYMORPHA 93 

(/) In the cells of a gemma do you find chloroplasts ? 
A nucleus? Oil drops? 

(g) Note the larger cells with clear contents from 
which the rhizoids will develop. Do they con- 
tain chlorophyll? 

(h) Make a drawing 50 mm. in diameter, showing 
all the features observed under D, 2 . 

(i) Draw the outline of an imaginary cross-section 
passing through the center of a gemma. 

The thallus. 

(a) Under high power study the surface cells and 
air-pore. How many guard-cells are there? 
Compare the air-pores of Marchantia with the 
stomata of a foliage-leaf of a higher plant, and 
of the moss and fern. Are they true stomata? 

{h) Study cross-sections of the plant mounted in 
clearing fluid. 

(c) The careful study of the structure of the foliage- 
leaf, already made, makes it unnecessary 
to give detailed directions for these observa-. 
tions. Frame your own questions, to be 
answered by observing the mounted section. 
Note especially whether the tissues are differ- 
entiated, and, if so, compare with a foliage-leaf 
in this respect. 

{d) Look for sections passing through air-pores, 
and compare their structure with that of the 
stomata of the leaf. What causes the surface 
appearance of the margins that delimit the 
areolae? 

{e) Describe the place and mode of origin of the 
rhizoids; of the cupules. 

(f) Is the thallus of the same thickness throughout? 

{g) Describe the chloroplasts. In some of the 



94 MORPHOLOGY AND LIFE HISTORY 

cells brown oil globules ma}* be observed. 
If these are found,, describe their location, 
and relative size. Do the cells that contain 
oil globules also contain protoplasm? Infer 
the source of the oil. 
Qi) Make drawings to illustrate all features observed 
under D, 3. 
E» Vegetative Propagation: 

1. There are tw^o ways in which Marchantia can 
propagate itself without the intervention of gametes. 
In the first place, a portion of the thallus, broken 
off , is capable of developing into a mature indi\adual. 
Somewhat, though not sharply, distinguished from 
this method is reproduction by means of the 
gemmae. State two differences between a gemma 
and a fern or moss spore. 

2. Incorporate the above facts into your notes at this 
point, using your own language, and state to what 
kind of reproduction each of the above methods 
belongs. 

F. Sexual Reproduction: 

I. Study plants having the upright stalks which bear 
the sexual reproductive organs. 

The antheridial branch 

Naked-eye Characters: 

(a) The stalks ha\ang the mushroom-shaped tops 
bear the antheridia, and are hence called the 
antheridial branches, orantheridiophores. The 
expanded portion borne at the summit of the 
stalk, is the antheridial receptacle. 
{h) Study and describe the stalks of the antheridio- 
phores. On what region of the thallus are these 



% MARCHANTIA POLYMORPHA 95 

structures borne? On which surface do they 
originate? State their average height in milli- 
meters. Describe the grooves on the surface. 
How many are there? 

(c) Describe the color of the stalk. Are stomata 
present? Epidermal hairs or other growths? 
If so, describe. 

(d) Do you find any antheridiophores that branch? 
{e) Describe carefully the appearance of the upper 

surface of the antheridial receptacle, noting 
the occurrence and distribution of any struc- 
tures or surface marks. 

(/) Is this surface perfectly plane ? If not, describe. 

(g) Make drawings, twice natural size, showing 
all points observed under F, i, {a)-{f), including 
a cross-sectional view of the stalk. 
Microscopic Characters: 

(h) Study and describe with drawings (5 cm. 
in diameter), the structure of the stalk of 
an antheridiophore as seen in cross-section. 

{i) Using prepared slides, study thin longitudinal 
sections passing through a receptacle and 
portion of the stalk. Is there a differentiation 
into epidermis and other tissues? Describe 
in detail. Note the intercellular air-spaces. 
In what part of the structure do they occur? 
Suggest any advantage these air-spaces may be 
to the plant. 

(k) Observe the chambers opening at the surface 
through necks, and containing the antheridia. 
How many antheridia in each chamber? De- 
scribe their shape, and mode of attachment. 
How many cells thick is the wall of the anther- 
idium? Do the wall-cells contain chlorophyll? 



g6 MORPHOLOGY AND LIFE HISTORY 

(/) Describe variations in the size of the antheridia, 
and explain. Locate them according to size. 

(w) Do you find papillae (paraphyses) at the base 
of the antheridia? If so, of how many cells are 
they composed? Describe their shape and 
appearance. 

(n) Describe the appearance of the contents of an 

antheridium. In the mature antheridium the 

contents are mature antherozoids or sperms. 

Younger antheridia contain sperm-mother- 

. . cells. Describe their appearance accurately. 

(o) Illustrate by suitable drawings all the features 
observed under F, i, {i)-{n). 

The archegonial branch 

Naked-eye Characters: 

(p) The stalks having the umbrella-shaped tops 
bear the female reproductive organs or arche- 
gonia, and are called archegoniophores. The 
expanded portion at the top of the stalk is the 
archegonial receptacle. 

(g) Do the archegonial and antheridial branches 
occur on the same plants? Measure the height 
of the stalks of several mature archegoniophores, 
and compare their average height with the aver- 
age height of the stalk of the mature antheridio- 
phore. Is the stalk of the archegoniophore 
grooved ? 

(r) Describe the markings of the upper surface of 
the receptacle, and compare it with the dorsal 
surface of the thaUus. Are air-pores present? 
Record the number of rays on your specimen. 
Compare several specimens on this point. 



MARCHANTIA POLYMORPHA 97 

(s) Describe the under surface. Note the fringed 
membranes (perichaBtium) . 

(/) Illustrate by drawings all structures observed 
under (p)-(s). 
Microscopic Characters: 

(u) Study and describe, with drawings (5 cm. in 
diameter), the structure of the stalk of an 
archegoniophore as seen in cross-section. Com- 
pare this with the antheridiophore (F, (h), p. 

95)- 

(v) Using prepared slides, study longitudinal sec- 
tions of the receptacle passing through one of 
its arms. If fresh or preserved material is at 
hand in sufhcient quantity, the study may be 
made from material "teased out" on the slide. 

(w) Study the tissues of the receptacle. Is there an 
epidermis? Stomata? Describe (a) the tis- 
sues just beneath the surface layer of cells; 
(b) those more deeply seated. 

(x) Observe the flask-shaped archegonia hang- 
ing from the lower surface of the receptacle. 
Can you distinguish two regions — ^venter and 
neck. Note the passage, or neck-canal, leading 
from the venter through the neck, and opening 
at the summit. How many cells thick is the 
wall of the archegonium? Compare with the 
archegonia of mosses and ferns. 

(y) Surrounding a mature archegonium observe the 
section of a cup-like structure, the perigynium. 

(z) Within the venter of an archegonium just 
matured observe a single-celled ovum, or egg. 

(aa) Make drawings illustrating all features shown 
under (w)-(z), and preserve the mounted 
section for subsequent study. 



98 MORPHOLOGY AND LIFE HISTORY 

G. Physiology: 

1. Is photosynthesis possible with the thallus? The 
antheridiophore ? The archegoniophore? What 
correlation do you find between structure and 
function in this respect in the archegoniophore? 

2. Explain the nutrition of the non-chlorophyll-bear- 
ing cells of the gemmae. What is their nutritive 
relation to the gemma as a whole? 

3. Is the gametophyte capable of an independent exist- 
ence? Thoughtfully consider and then describe 
the correlation between structure and function in 
tills respect. 

4. In mature specimens grayish drops of liquid may 
often be found exuding on the dorsal surface of the 
antheridiophores. This hquid contains active an- 
therizoids, or sperms. Mount some of it in water, 
and, under high power, observe the motion, organs of 
motion, and other structural features of these sperms. 

5. When longitudinal sections of mature archegonia 
are mounted in water containing active sperms the 
beha\-ior of the latter toward the former may be 
readily observed. If your material is suitable, 
make these studies. 

6. How, only, can the sperms reach the egg? What 
external conditions would be favorable for this ? 

7. Of what advantage is it to the sporophyte to have 
the egg retained in the venter of the archegonium? 
Would this be of as great advantage in any aquatic 
plant as in a land plant? Why? 

8. Is the small size of the sperms of any special advan- 
tage to the plant? Explain. 

9. Explain any advantage in the greater height of the 
mature archegoniophore over that of the antheridio- 
phore. 




MARCHANTIA POLYMORPHA 99 

10. Enumerate several facts that insure a wide distribu- 
tion of Marchantia. 



The Sporophyte 

A . Origin of the Sporophyte: 

I. What is the process of the fusion of the egg and 
sperm called? What is the body that results 
from this fusion called? This body, by successive 
cell-division, develops into the sporogonium or 
sporophyte. 

B. Naked-eye Characters: 

1. In a mature specimen observe the small bell- 
shaped organs (sporangia), pendant on a stalk 
between the perichaetia. The sporangia and stalk 
together form the sporogonium, or sporoph3rte stage 
of Marchantia. In fresh mature specimens an 
orange-colored mass containing spores is easily seen 
at the end of the sporophyte. Are the sporogonia 
borne on a line with the rays or between the rays? 

2. Make drawings, four times natural size, showing the 
archegoniophore as seen from {a) the top; (b) the 
side; (c) the underside. 

3. After making the drawings, as directed in B, 2, 
carefully dissect out one mature sporogonium and 
place it in a watch-glass to examine. Make a 
drawing 50 mm. long, showing all features observed, 
labeHng the foot, stalk, and sporangium. Write a 
brief but clear description of the sporogonium. 

C. Microscopic Characters: 

' I. If prepared slides are available of sections passing 
through the archegonia (F (x) above), find various 
stages in the development of the sporophyte within 
the archegonium. In nearly mature specimens 



100 MORPHOLOGY AND LITE HISTORY 

observe the attachment of the sporophyte to the 
receptacle by means of the foot. This study may be 
made to advantage with fresh or preserved material 
teased out on the slide. In such preparations there 
will be observed, surrounding the sporogonium, the 
membrane formed by the growth of the perigynium. 

2 . In the mount already made (or in a fresh mount of 
the orange-colored mass referred to in {B, i, p. 99), 
observe the spore-mother-cells (sporocytes) or, in 
older specimens, the spores (in strands or separate, 
depending on the stage of development), and the 
elongate elaters. What is the size of the spores, and 
the number of cells of which they are composed? 
Describe their shape, and any surface marks ob- 
served. Describe any marks on the elaters. Of 
how many cells is an elater composed ? Mount, dry, 
some of the mass that contains elaters, and observe, 
under the low power, their behavior as water is 
added. Draw. 

3. Are the antheridiophores and archegoniophores 
sex4ial organs ? Why? What are the sexual organs 
of Marchantia? 

4. Name and classify (sexual or asexual) four different 
kinds of reproductive bodies produced by this plant. 
Consider carefully whether the spores, produced 
by the sporophyte, are sexual or asexual reproduc- 
tive bodies. 

D. Physiology: 

1. Can photosynthesis take place in the sporophyte? 
Explain your answer. 

2. From what source, by what organ or organs, and 
by what physical process does the sporophyte ob- 
tain its water and dissolved food? Compare it 
with the gametophyte in this respect. 



MARCHANTIA POLYMORPHA 



lOI 



E. Comparison of Gametophyte and Sporophyte: 

1. Compare the degree of development or organiza- 
tion of sporphyte and gametophyte. 

2. Copy the following table into your laboratory note- 
book and mark x after the word gametophyte or 
sporophyte in the proper column. 

Table II 









m 


}. "^ 


(U 


w 


r-i 


rCO 


>, 








1? 


'H ^ 




-t-> 







td 








bo 


(^ (U 


rt 


F 


K 


.Q 










«H 


.rt +J 


t^ 


o; 




-^ -. 


Generation 




0. 


o 


^ (U 

'2 lu 


P. 
w 


CO 


CO 

o 

• p< 


to «j'J3 
C > o 


to'43 
do 
O 3 




>H 


2 


'-J 


rt 


3 


M «> 


•u nSTJ 


•^•a 




0) 


13 


o 
o 




to 

> 


13 
o 


CIS 


O-tJ o 

C <U »H 


y o 
3 R" 




^ 


o 


p^ 


Oa 


►-5 


Oh 


m 


f^ > K 


HH U 


Gametophyte 





















Sporophyte 



















3. State reasons why you consider Marchantia higher 
or lower than {a) the moss; {h) the fern. 

4. Diagram the life cycle of Marchantia, as directed 
for the fern (7, 11, p. 78). 

5. Indicate the life history of Marchantia for three gen- 
erations, as directed in /, 10, p. 78. 

6. Does the gametophyte ever produce another game- 
tophyte directly? Does the sporophyte ever pro- 
duce another sporophyte directly? If so, explain 
how. What phase intervejies between two gameto- 
phytes in the alternation of generations? Between 
two sporophytes? Is this always the case so far 
as your own studies show? Explain what is meant 
by the expression, ''alternation of generations." 



Fucus vesiculosus (Bladder wrack) 

A. Classification: 

Di\dsion I. Thallophyta. 
Subdivision I. Algae. 

Class III. Phaeophyceae (brown algae). 
Order. Fucales. 
' Family. Fucaceae. 
Genus. Fucus. 
Species, vesiculosus L. 

B. Habitat: 

I. Ascertain the habitat of this plant from your read- 
ing, class discussion, or field trip, and record it 
in your laboratory notes at this place. 

C. Naked-eye Characters: 

1. These characters may be best studied by floating a 
fresh specimen in a dish of sea-water. Material 
preserved in formalin should be rinsed under the 
tap, and then floated in fresh water. 

2. Describe the color, shape, and size of the thallus. 
Does it form lateral branches or approximately 
equal terminal branches (dichotomy, forking). 

3. Do you find any holdfasts, or organs of fixation? 
If so, describe them. State reasons why you think 
they are true roots or not. 

4. Is there a midrib? A stalk, or stipe? Do you 
consider that the plant is differentiated into root, 
stem, and leaf? Give reasons. 

5. Describe the distribution of bladders. Why is this 
species called ^' vesiculosus?^^ 

102 



FUCUS VESICULOSUS IO3 

6. Observe the swollen tips, receptacles. Do the tips 
of all the branches bear receptacles? How may 
they be distinguished from the bladders? 

7. Carefuly note the dot-like projections on the re- 
ceptacles. Find the circular openings in these pro- 
jections, the ostioles. 

8. Do you find ostioles elsewhere than on the recep- 
tacles? If so, describe their distribution over the 
surface of the thallus. Where are they not found? 

9. Observe carefully the emarginate tips of the 
branches that do not bear receptacles. Do you 
find a groove in these tips? If so, is it in the plane 
of the thallus, or not? 

10. Make careful drawings, natural size, showing all 
points noted under C. 
D. Microscopic Characters: 

I. Mount in water thin cross-sections taken through 
the thin expanded portion of the thallus, and study 
under the low power. 

Note the differentiation of the tissue into central 
tissue or medulla, and a cortical tissue. How are 
the two distinguished? 

3. Observe that the outer layer of cells of the cortical 
tissue is further differentiated into an epidermoidal 
tissue. Describe it. This outer layer is not a true 
epidermis, like the outer layer of cells of the leaf. 
In the younger portions of the thallus its cells, by 
division, give rise to the cells which form the under- 
lying tissues. None of the algce possess a true 
epidermis. 

4. Is starch present in the cortical tissue? Chlo- 
rophyll? Note the layer of cuticle on the outer 
cell- walls of the epidermoidal layer. 

5. Note that the ceils in the medulla tend to form a 



I04 MORPHOLOGY AND LIFE HISTORY 

thread-like network. Does starch occur in this 
tissue? Some of the cells unite, end to end, form- 
ing tubes to conduct liquids. Can you detect this? 

6. Between the cells of both cortex and medulla is a 
mucilaginous layer, formed by the swelling and 
chemical transformation of the middle lamella, 
or layer that separates adjacent cell- walls. 

7. Make a drawing showing the differentiation of 
tissues from the surface to the center of the thallus. 

8. Sterile Conceptacles: Secure sections passing through 
one or more of the ostioles that do not occur on the 
receptacles. These ostioles will be found to open 
into spherical or pear-shaped cavities (conceptacles), 
imbedded in the cortical tissue. In viewing a cut 
end of the thallus with the naked eye, these ca\dties 
appear as minute dots underneath the epidermoidal 
layer. 

9. Observe in these conceptacles, under the low power, 
numerous long hairs (paraphyses). Of how many 
cells is each composed? Do they extend through 
the ostioles to the surface? With what are they 
connected? 

E. Physiology: 

1. Of what advantage to an aquatic plant may the 
air-containing bladders be? 

2. Does the plant grow attached to a substratum? 
If so, how? 

3. How do you think the plant takes in its food ele- 
ments ? 

4. Ascertain if the plant has chlorophyll. Is photo- 
synthesis possible? 

5. Would it be an advantage to this plant to have a 
system for conducting liquid nutrients from one 
place to another? Is such a system present? 



%• FUCUS VESICULOSUS 105 

In attempting to answer this last question recall 
the habitat of Fucus. 

F. Vegetative Propagation: 

1. Vegetative propagation is accomplished by the 
breaking off of branches which may float away 
and become established as new individuals. 

2. Frequently, by a process of regeneration, dwarf 
branches are formed where portions of thallus 
have been torn away. Do you find instances of 
this in the material at hand? 

G. Sexual Reproduction: 

1 . The sexual reproductive organs of Fucus are borne 
in fertile conceptacles, imbedded in the cortical 
tissue of the receptacles. In Fucus vesiculosus the 
conceptacles containing the female organs are on 
different plants, i.e., the plants are dioecious. In 
other species they are both on the same plant, while 
in still other species {e.g., F. edentatus) both kinds 
of organs are in the same conceptacle. In the two 
latter cases the plants are monoecious. 

2. The Male Conceptacles: 

(a) Examine a longitudinal section of a male 
conceptacle, passing through the ostiole. Note 
the outline of the cavity. Describe its wall. 

(b) Observe the filaments (paraphyses) within the 
cavity, and describe the length, diameter, 
shape, and structure of one of them. Do any 
of these filaments project through the ostiole? 
Explain the feehng as a receptacle is taken be- 
tween the thumb and fingers. 

{c) Are the filaments that pass through the ostiole 
similar to those that do not? On the latter 
observe the small ellipsoidal organs antheridia. 
Where and how are they attached? How 



Io6 MORPHOLOGY AND LITE HISTORY 

many on each hair? Obsen'e their contents, 
the sperms fantherozoids, spermatozoids) . 

(d) Make a drawing at least 50 mm. in longest 
diameter, illustrating all the above structures. 

3. The Female Conceptacles: 

(a) Study a longitudinal section passing through 
a female conceptacle, as directed above 
(G, 2). Compare them in all points with 
the male conceptacles. 

{h) Observe the egg-bearing organs, oogonia. 
Describe their shape, size, color, place and 
mode of attachment, and number, and 
compare them in these respects with the 
antheridia. 

(c) Describe the structure of the wall of the 
oogonium, noting especially whether it is 
composed of cells. 

{d) Study the contents foospheres, or eggs) of 
the oogonium. How many are there? 

(e) Make drawings showing all these points, 
as directed in G, 2(d). 

4. The Fertilization of the Egg: 

{a) Observe fresh plants that have been hang- 
ing in the air for about six hours, and see 
if you can observe an orange-colored fluid 
exuding from the ostioles of the male con- 
ceptacles. If so, mount some of this fluid 
in sea-water and examine it under the high 
power. 

(&) Note the antheridia floating about, and the 
escaped sperms. Do the latter possess the 
power of locomotion? If so, how do they 
move? Describe their shape, relative size, 
and color. 



FUCUS VESICULOSUS 107 

(c) Make a drawing of three or four sperms, 
with the body about lo mm. long. 

(d) In a similar way, find the fluid exuding 
from the female conceptacles. What is its 
color? Mount a drop of it in sea- water 
and examine with the high power. 

(e) Do you find any oogonia? Any free eggs? 
If so, how are the latter freed from the 
oogonia? Do they possess the power of 
locomotion? Compare their size with that 
of a sperm. 

(/) Make a drawing (50 mm. in diameter) of 
an egg. By the side of the egg draw three 
sperms to the same scale, showing the 
relative size of egg and sperm. 

(g) Prepare a mount containing both eggs and 
sperms, and endeavor, if possible, to fol- 
low the action of the sperms toward the 
egg, and the fusion of the two cells. With 
what act is fertilization completed? 

(h) Do you consider Fucus sl more highly or a 
more lowly organized plant than Mar- 
chantia? Give reasons for your answer. 



Vaucheria sessilis (Green felt) 

A. Classification: 

Division I. Thallophyta. 
Subdivision I. Algae. 
Class II. Chlorophyceae. 

Order. Siphonales (Siphon- algae). 
Family. Vaucheriaceae. 

Genus. Vaucheria. (The only genus in 

the family.) 
Species, sessilis (Vauch.) DC. 

B. Habitat: 

From your reading, class work, and material at hand, 
ascertain and record at this point in your notes the 
kind of locahties where this plant occurs. 

C. Naked-eye Characters: 

Describe the color and ''feel" of this plant, and the 
general form of the plant-body. What is the signifi- 
cance of the common name "green felt"? 

D. Microscopic Characters: 

1. Mount a portion of the material in water. 

2 . Is the plant branched ? 'If so, is the branching lateral 
or dichotomous {i.e., forked)? 

3. Do you find cross-walls? Does the plant seem to 
be composed of cells? What is the outline of its 
cross-section? 

4. Can you detect any signs of division into root and 
shoot? Do all portions of the filaments appear 
equally fresh and vigorous? Describe. 

5. Do you find, on the end of any of the filaments, 

108 



^. VAUCHERIA SESSILIS IO9 

holdfasts? If so, describe them, and state their 
use to the plant. 

6. Can you detect one or more nuclei? Any vacuole 
or vacuoles? Any individual chromatophores or 
chloroplasts? If so, what is their position and 
shape? 

7. Describe the arrangement of the protoplasm within 
the filament. 

E. Physiology: 

1 . Explain whether, or not, photosynthesis and respira- 
tion are possible with this plant. 

2. Do you find any chromatophores dividing? 

3. Do you find oil globules within the plant? Test 
dechlorophyllized plants with iodine for starch. 

4. How are mineral matter and carbon taken into this 
plant? Explain the need or lack of need of special 
structures for conducting food and food elements 
from one part of the plant to another. Are such 
structures present? 

5. Why is the plant not crushed by the weight of the 
water (when it grows in water), or by the cover- 
glass? 

6. Can you detect any movement of the protoplasm? 
Observe carefully on this point. 

7. Make careful drawings showing all features to which 
attention has been directed under D, and E, 2. 

F. Asexual Reproduction: 

1. Carefully examine the tips of numerous filaments 
and see if you find any of them slightly enlarged, 
and cut off from the rest of the filament by a cross- 
wall. Such a differentiated portion of the thallus 
of Vaucheria is a sporangium; its contents a spore. 

2. If you are fortunate enough to have material at a 
suitable stage of development, you may, by care- 



no MORPHOLOGY AND LIFE HISTORY 

ful obser\'ation, observe a spore escaping from the 
opening in the tip of the sporangium. If so, give 
careful attention to the mode of locomotion of the 
spore, and describe how its locomotion is accom- 
pHshed. Since it has motion (as animals do) it is 
called a zoospore. The zoospore soon comes to 
rest. 

3. If the material contains germinating zoospores, 
carefully describe them. 

4. Make drawings illustrating all you have observed 
under F. 

G. Sexual Reproduction : 

1. In "fruiting" material, observe the lateral organs 
that bear the gametes. These are the reproductive 
organs. As is seen, they are of two kinds. 

2 . The larger, oval-shaped organ is called the oogonium. 
Is the oogonium cut off from the parent filament 
by a wall? On one side obser^x the rostnim, or 
beak, through which is an opening or pore. In 
material at a suitable stage may be observed a 
portion of the contents of the oogonium being 
voided or discarded. The protoplasm that re- 
mains in the oogonium now becomes organized into 
the larger gamete, or egg (oosphere). Is its wall 
composed of ceUs, or is it a unicellular organ? 

3. By the side of the oogonium^ find a slender branch, 
usually recurved at the end. Is this branch cut off 
from the parent filament by a wall? Is .the tip 
cut off from the rest of the branch? This tip bears 
small gametes, that svrim about by means of two lash- 
like ciKa. They are the spermatozoids, or sperms. 

^If the species is V. geminata, instead of V. sessUis, the reproductive 
organs will be found on the same lateral branch. The above directions 
will not apply in detail to any species except V. scssilis. 



VAUCHERIA SESSILIS III 

What is the organ that bears the sperms called? 
The base of the antheridial branch is the pedicel, 
or stalk. 

4. Can you detect any sperms escaping? If so, 
observe and describe them carefully. See if you 
can find any empty antheridia. 

5. Make careful drawings showing all points observed 
under G. 

6. Is there a division of physiological labor in Vauch- 
eria? Explain in detail. 

7. Show, by a diagram, the life cycle of Vaucheria. 

8. State the difference between conjugation and 
fertilization. 

9. Draw an ideal diagram of a complete plant, showing 
all structures, and stages of their development. 



Spirogjra sp. (Pond scum, Green silk)^ 

A. Classification: 
Dmsion I. Thallophyta. 

Subdivision I. Algae. 
Class II. Chlorophyceae. 
Order. Conjugales. 
Family. Zygnemaceae. 
Genus. Spirogyra. 

Species, sp. {i.e., not determined). 

B. Habitat: 

Ascertain from your own observations and from the 
text, and record at this point in your notes, the habitat 
of Spirogyra. 

C. Physiology: 

1. Explain, clearly but concisely, how the bodily form 
of this plant is maintained. Account for any 
variations in the shape of the cells. 

2. Do you find any roots or other organs for anchoring 
the plant to the substratum? Do you think the 
plant is suitably organized for growing in running 
water? Explain. State a reason why roots are 
not necessary for this plant. 

3. Explain the presence or absence of stomata. Do 
you find a cuticle?^ Is photosynthesis possible with 
Spirogyra? Respiration? Explain. 

1 The morphological characters of this plant have already been studied 
(pp. 11-15). They should now be carefully reviewed, preparatory to the 
consideration of the physiology and reproduction of the plant. 

2 True cuticle does not occur, but a modification of the outer portion 
of the cell-waU, called the sheath, and which gives the plant its sHppery 
"feel," is similar to cuticle, though not identical with it. This sheath 
is difficult to observe directly, though it may sometimes be identified on 
the outside of the filament at the places where the cross- walls occur. 

112 



^. SPIROGYRA SP. 113 

4. Can you detect any difference between the cells, 
physiologically? From your own observations do 
you think there is any correlation between the struc- 
ture of cells and their function? Explain clearly. 

5. Is there any evidence in Spirogyra of a correlation 
between structure and environment?- Explain. 

D. Asexual Reproduction in Spirogyra: 

I. From what you have already learned of Spirogyra, 
state the possibiKtes of vegetative propagation in 
this plant. 

E. Sexual Reproduction in Spirogyra: 

1. Use fresh material, if possible; otherwise preserved 
specimens, or prepared sKdes. 

2. Observe the various stages in the fusion of two cells 
(gametes). Do the fusing gametes belong to the 
same, or to different filaments? Observe the 
conjugation-tubes connecting adjacent filaments.^ 
What is their function? Their relative diameter? 
Try to find tubes in various^ stages of formation. 
Are their distal ends open before they come into 
contact? How is the opening made? Do the tubes 
grow together or merely touch each other? 

3. Does conjugation seem to be a function of all the 
cells of the filament, or of certain cells only? 

4. Do the gametes pass from either filament to the 
other, or do the cells of a given filament all behave 
alike in this respect? In this connection see 
whether all the zygospores occur in one filament, 
or not. 

^The form of conjugation described in the outline above, is termed 
" scalarif orm " (ladder-like). Another type, known as "lateral" con- 
jugation may frequently be met with, in which the gametes are formed by 
adjacent cells of the same filament. In less frequent cases the protoplast 
of a single cell organizes itself into a reproductive body (aplanospore) 
without conjugation. This process is a type of parthenogenesis. 



114 MORPHOLOGY AND LIFE HISTORY 

5. Does the cell- wall of the receiving cell serve as the 
cell-wall of the zygospore, or does the latter form a 
new wall? 

6. In a sentence define the term supplying cell, using 
the words gamete and conjugation. 

7. If fresh material is studied, describe any observed 
differences in color between the mature zygospore 
and the non-conjugating cells; any structural dif- 
ferences between the cells of a suppling filament 
and those of a recei\dng filament. Do you observe 
any e\ddence of sexual differentiation in the 
filaments? 

8. Can you detect any constant structural difference 
between supplying and receiving cells in size, or in 
the size of the cell organs {e.g., width of chlorophyll 
bands, diameter of pyrenoids, etc.)? 

9. Explain whether Spirogyra represents a condition 
of isogamy or of heterogamy. 

10. Make drawings of all the following features shown 
by your material, with each cell about 50 mm. long. 
{a) Two adjacent cells in which the conjugation- 
tubes are just beginning to develop. 

(h) Two adjacent cells in which the conjugation- 
tubes have just met. 

{c) Two adjacent cells in which the active (supply- 
ing) gamete is passing through the conjugation- 
tube. 

{d) Two adjacent cells in which the passage is 
complete. 

{e) Two adjacent cells after conjugation is com- 
plete. Show carefully and accurately the details 
of structure of the zygospore. 

11. Study stages in the germination of the zygospore 
as shown on the chart. State, in order, the proc- 



SPIROGYRA SP. 



115 



esses that take place in the formation of the 
new plant (mature zygote) from the zygospore. 
Compare the plant of the new generation with 
its parents. 

12. Is there a physiological division of labor in this 
plant? Explain in detail. 

13. Draw a diagram showing the ancestors of a plant 
of Spirogyra for three generations. 

14. To complete your notes on Spirogyra, write, at 
home, and before the next laboratory period, as 
clear and well-worded an account as you can of 
the life history of the plant. 

15. Arrange ferns, algae, mosses, liverworts, in a 
vertical column in the order of the complexity of 
their organization, placing the more highly organ- 
ized near the top of the column. Write a clear 
statement of the reasons for your arrangement 
of the above classes. 



Pleurococcus vulgaris (Green slime) 

A. Classification: 
Division I. Thallophyta. 

Subdivision I. Algae. 

Class TI. Chlorophyceae (green algae). 
Order. Ulotrichales. 

Family. Chaetophoraceae. 
Genus. Pleurococcus. 
Species, vulgaris Menegh. 

B. Habitat: 

I. From the material given you, infer where this plant 
grows. Leave a blank space in your note-book, 
and before the next laboratory period, record further 
observations on this point, made out of doors, 
noting especially the following points. Does the 
plant appear to be more abundant on one side of 
the object on which it grows than on another? 
Describe and explain. In general, what external 
conditions seem to favor its growth? Do you ever 
find it intimately associated with other plants? 
Describe. 

C. Naked-eye Characters: 

I. Describe the color of a colony of Pleurococcus. 
Can you distinguish the shape or other characters 
of an individual plant? 

D. Microscopic Characters: 

I. With the needle carefully scrape off a bit of the 
plant from a piece of moist bark or wood, and 
mount it in water. 

ii6 



PLEUROCOCCUS VULGARIS I17 

2. Is the body of this plant differentiated into root, 
stem, and leaves? Is it composed of cells? If so, 
of how many? Make a thorough study of this 
point before you answer and thoroughly consider 
how many cells you think are necessary in order to 
make one plant. State your opinion, with reasons. 
Compare the arrangement of the cells with those in 
Spirogyra. 

3. Describe the color and shape of individual cells. 
Describe and account for any variations observed 
in the shape of the cells. 

4. Carefully describe all the cell-organs you can 
identify in this specimen. Name all the cell-organs 
you cannot find. How does the chlorophyll occur 
in the cell of Pleurococcus? If you find chloroplasts 
state how many, their location, and relative size. 

5. Make careful drawings showing all features so far 
as observed, with none of the cells less than 15 mm. 
in longest diameter. 

E. Physiology: 

1. How does Pleurococcus remain fixed to the sub- 
stratum on which it ' grows ? Are there special 
organs for this purpose? 

2 . Are there special organs for the taking in of nourish- 
ment from the substratum? How can the plant 
accomplish this process? 

3. Is photosynthesis possible with P/ewroc<?cc#5.? Give 
reasons for your answer. Are stomata present? 
Why? Describe how CO2 can be taken into the 
cell. 

4. Are there any special organs of respiration? How 
can this process take place? 

5. Do you think Pleurococcus is sensitive to stimuli 
from without? Give reasons for your answer. 



Il8 MORPHOLOGY AND LIFE HISTORY 

F. Reproduction: 

1. Do you find any cells that appear to be dividing? 
If so, carefully describe their appearance. What 
are the indications that a cell is dividing? 

2. Do the cells tend to remain united after cell -divi- 
sion? Is this true of all of them? Describe. 

3. Make three diagrams, showing (a) the life cycle of a 
Pleurococcus plant; (b) the descendants of one plant 
for six generations ; (c) the ancestors of one plant for 
six generations. 

4. Is there a division of physiological labor in this 
plant, or are all life functions performed by every 
cell? 



Bacteria^ 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 
Class II. Schizomycetes. 
Order. Bacteriales. 
Family. Bacteriaceae. 
Genus. Bacillus. 

Species (e.g.). suhtilis (Ehrenb.) Cohn. 

B. Habitat: 

Bacteria are found almost everywhere except, possibly, 
far out at sea and upon the tops of lofty mountains. A 
very good source from which to take material for this 
exercise is the jar in which Saprolegnia was grown. If 
this is not now available use stagnant water from any 
source, or pickings from your teeth, using for this pur- 
pose a new toothpick. 

C. Microscopic Characters: 

1. Clean cover-glasses thoroughly and pass them 
through the flame of an alcohol lamp several times, 
taking care not to break them. If a hanging drop 
preparation is not available a fairly satisfactory 
substitute may be made by cementing to a clean 
glass slide, with Canada balsam, two beheaded 
pins, laid horizontally, about twelve mm. apart. 

2. With a sterilized needle put a large drop of water 
from the jar, thought to contain bacteria, on the 



^ The directions for the study of bacteria were prepared by Prof. James 
S. Compton, Eureka College Eureka, Illinois. 

119 



I20 MORPHOLOGY AND LITE HISTORY 

clean cover-glass; invert the cover-glass and lay 
it upon the pins so the drop will be in the center of 
the glass. Place the sKde on the stage of the 
microscope. Focus with great care, so as not to 
break the fragile cover-glass or wet the objective. 
The bacteria should be just ^■isible with the low 
power; with the high power you should be able to 
make satisfactorv studies. 

3 . Observe the bacteria in the mount. Note variations 
in shape: the spherical or coccus forms, the rods or 
bacUlus forms, and, usually in such material, curved 
or spirillum forms. Note also the rapidity and char- 
acter of the motion. Do they all move? Some 
have a \ibratory motion; others move forward in a 
direct Hne. 

4. The technique of staining is too difficult for the 
beginner in botany. The instructor will furnish 
stained and mounted bacteria for examination with 
the high power. In some instances the instructor 
may use the oil immersion if it seems ad\'isable. 
The following t}'pes are suggested for this study: 
Bacillus subtil is (hay bacillusV 

Bacillus proteus (decay), stained to show flagella. 
Bacillus tuherciddsis. 
A Streptococcus and a Spirillum. 
In your notes enter data on ia) comparative size, 
{h) absorption of stain by bacteria, (c) grouping, 
{d) source. 
D. Naked-eye Churackrs: 

I. Prepare agar-agar culture medium, or use prepared 
medium supplied in a test-tube by the instructor. 
Melt the agar carefully over an alcohol or Bunsen 
flame, beginning at the top. (Why begin at the topP'i 
When it is melted pour the agar into a sterile Petri 



BACTERIA 121 

dish, taking care to protect the dish (Why?) by hold- 
ing the lid directly over it, but far enough above to 
allow room for the test-tube. Any standard work 
on bacteriology will show how this is done, or the 
instructor may demonstrate for the class. After 
pouring replace the lid, and set the dish outside the 
window, or in the ice box, to cool. When cool and 
firm the dish may be infected and put away in a 
drawer or dark store room for a week. 

2. Infect the agar-agar by removing the lid of the Petri 
dish and exposing the surface to the air of the labora- 
tory, hall, hbrary, or other place where people come 
and go. The exposure should be made for a defi- 
nite time, uniform for all exposures, preferably three 
to five minutes. 

3. When the bacteria have grown sufficiently to be 
visible in colonies (requiring usually a week or ten 
days, depending upon the temperature), bring out 
your cultures and examine them. Count the num- 
ber of colonies visible to the naked eye, or with a 
hand lens, and, on the basis of one bacterium as 
the source of each colony, compute the number of 
bacteria falling per square centimeter per minute 
at the time of infection. 

4. Observe carefully the differences in the colonies as 
regards (a) color, (b) elevation, (c) luster, (d) 
rapidity of growth. 

5. Take two test-tubes of the same liquid culture- 
medium, preferably bouillon, and infect them in 
the same way. Boil one over a flame. Label 
both and set them away where they will not be 
disturbed. Observe at frequent intervals (e.g., 
daily), for a week or ten days, noting especially 



122 MOKPHOlJOGir Al^ 



tmbiditj and odor. If the instructor deems it 
ad*iaUe.sameiiieiiibeisoftliedass,iiKtead<rfl«^ 
ing the contents off cmic tnbc after infectiom, may pat 

I - zndanj bacterial cdlstliat seem to be divid- 

i z ^ Is tfaeze a tendency for the ceils to remain 
— ti ^: rr divfeion? Read in snne standard 
- :l 1:1:: rria about the formation di spares. 



Phycomyces nitens (or Rhiozopus nigricans) 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 

Class III. Phycomycetes (alga-fungi). 
Order. Mucorales (the molds). 
Family. Mucoraceae. 
Genus. Phycomyces. 
Species, nitens Kantze & Schmidt- 

B. Habitat: 

I. Upon what substratum is the Phycomyces growing? 
What atmospheric condition seems to be most 
favorable to its growth? 
C Naked-eye Characters: 

1. Describe in detail the appearance of this plant as 
it grows. What is its color? Describe any varia- 
tions in color. 

2. Note .the aerial filaments or hyphaa. Do they 
grow erect or horizontally? How many milli- 
meters long are they? 

3. On the ends of some of them observe the enlarged 
structure, the sporangixim. Describe its shape. 
From its name, sporangium, what do you infer that 
•it contains? Hyphae that bear sporangia are 
sporangiophores. What does the term literally 
mean? 

4. Compare the height of the sporangiophores bearing 
young (yellowish) sporangia, with that of those 
bearing more mature (dark-colored) sporangia. 
Explain the significance and advantage of this. 

5. Using the hand lens, note the vegetative hyphse 

123 



124 MORPHOLOGY AND LITE HISTORY 

that grow into the substratum (substance on which 
the fungus grows), and over its surface. These 
filaments constitute the mycelium. Compare their 
diameter with that of the sporangiophores. Do 
they appear to branch? 
6. Make a drawing, illustrating all points observed. 
Make a diagram showing, in order, the relative 
heights of six sporangia of various ages. Indicate 
the scale used. 

D . Vegeta five Propagation : 

1 . If Rhizopiis nigricans is used, study, with the naked 
eye or hand lens, the formation of stolons by this 
plant, and describe in full, with drawings, this proc- 
ess of propagation. This plant {Rhizopiis nigricans) 
was at one time called Mucor sfolonifer. Explain 
the appropriateness of this latter specific name. 
The generic name, Rhizopus (root-Hke foot), refers 
to the branching mycelial h^-phae, which form at the 
tips of the stolons. Explain the significance of the 
specific name nigricans (black). 

2. How does Pky corny ces nitens increase vegetatively? 

3. Study and draw stages in the germination of spores 
that have been in sugar solution for twenty-four 
hours. (Use spores of Pkycomyces or Sparodinia, 
as spores of Rhizopus do not germinate readily in 
sugar solution.) 

E. Microscopic Characters of the Mycelium: 

1. Mount in water a small portion of the substratum 
with the mold attached, and, if necessary, very 
carefully tease it out with the needles. 

2. Study the myceHum. Is it branched? Are the 
myceKal h}-phae of the same diameter throughout? 
iVre cross-walls present? If so, describe their 
frequency. 



% PHYCOMYCES NITENS 1 25 

3. Make a drawing to illustrate the above points. 

F. Physiology: 

1. Describe the color of the sporangiophore and 
sporangium as seen under the microscope, and state 
whether this color is in the cell-wall or in the cell- 
contents. 

2. If you detect any motion of the protoplasm (best 
seen in young sporangiophores) describe it accu- 
rately. Is it a true circulation {i.e., in various 
directions in a closed circuit), a rotation {i.e., up 
one side of the filament and down the other), 
or a streaming {i.e., all currents apparently toward 
one and the same end of the filament). Suggest 
any advantage this motion would be in the nourish- 
ing of the plant; in the formation of sporangia. 

3. Make a drawing of a portion of the hypha, at least 
15 mm. wide, showing the appearance of the con- 
tents, and, with arrows, the direction of motion. 

4. What foods does this fungus need? From where 
must they be obtained? Are they soluble? Can 
Phycomyces take in soHd food? What process is 
necessary in our own bodies before we can utilize 
solid food? Must Phycomyces perform a like 
function? Is there a special organ for such a 
function? Must the process go on inside or out- 
side of the body of the plant? Why? 

5 . Is photosynthesis possible with Phycomyces? Why ? 
How must it get its carbohydrates? 

6. Does Phycomyces respire? Give a reason for your 
answer. 

7. What is the most obvious and important difference 
between the cells of Phycomyces and of Spirogyra? 

G. Asexual Reproduction: 

I. Study a sporangiophore. Is it of the same diameter 



126 MORPHOLOGY AND LIFE HISTORY 

throughout? Are cross-walls anywhere present? 
If so, describe their location. 

2. Is the sporangium borne on the tip of the sporangio- 
phore, or at one side? Are its contents separated 
from those of the sporangiophore ? If so, how? 
Compare, on this point, young and old sporangia. 
Is there more than one sporangium on a sporangio- 
phore? Within the wall of the sporangium observe 
the central columella, surrounded by the spores 
Describe the shape of the columella. Are the 
spores numerous or few within one sporangium? 
Look for cases where the wall of the sporangium 
has ruptured, and the spores are mostly scattered, 
leaving the columella naked. 

3. Ilustrate by drawings all features observed under 
G, I and 2. Make the sporangium at least 20 mm. 
in diameter. 

4. Describe the shape, relative size, color, and surface 
markings (if any) of the spores. 

H. Sexual Reproduction: 

Note. — For this study S porodinia rmiy he suhstitntQd, 
as it more readily yields suitable material. 

1. Find conjugating branches. Describe their shape. 

2. Find mature conjugating branches with the end 
contents cut off to form gametes. The remainder 
of the branch is now called a suspensor. 

3. Find, on still more mature material, the gametes 
fused. What is the resulting structure called? 
Describe its appearance. If the material is suitable, 
descibe the germination of this stucture. 

4. Illustrate, with a drawing, all features observed 
under H. Make the suspensors at least 25 mm. 
long, and other structures in proportion. 



Saprolegnia (Water mold) 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 
Class III. Phycomycetes. 
Order. Saprolegniales. 
Family. Saprolegniaceae. 
Genus. Saprolegnia. 
Species, sp. (i.e., not given). 

B. Habitat: 

I. The spores of this fungus are widely distributed, 
and develop readily under suitable conditions. 
Such conditions are commonly realized when a dead 
fly is placed in a dish of pond water, especially 
when some alga is added. The fungus will be 
sufficiently developed for study within five to seven 
days. 

C. Naked-eye Characters: 

1. Carefully observe the hyphae as they grow, forming 
a halo about the body of the fly. What is the 
diameter of the halo? Its shape? Does its 
shape seem to be influenced by the shape of the fly's 

' body? Do the filaments grow vertically upward 
and downward or only horizontally? What is the 
color of the halo? 

2. Estimate the average length of the hyphae. 

3. Can you detect any evidences of the formation of 
sporangia at the tips of some of the hyphae, and of 
sexual reproductive organs near the body of the fly? 
Use a hand lens if necessary. 

127 



128 MORPHOLOGY AND LIFE HISTORY 

4. Make a drawing, about 25 mm. in longest diameter, 
showing the appearance of this fungus as it grows on 
the body of the fly. 

D. Microscopic Characters: 

1. With the needle or scalpel carefully remove a few 
filaments and mount them in water. Examine 
with the low power. 

2. Make careful comparisons of the tips of hyphas 
enlarged to form sporangia with those not thus 
modified. Describe the appearance of the contents 
in each. 

3. Do you find any cross- walls in the filaments? 

4. Do you find vacuoles? Plastids? Nuclei? 

5. Make a drawing showing the appearance of the tip 
of a vegetative filament (10 mm. in diameter). 

E. Nutrition and Growth: 

1 . See if you can find hyph^e bearing empty sporangia. 
If so, do you find the hypha continuing its growth 
in length within the empty sporangium? Illus- 
trate this point by a drawing. 

2. Where do the vegetative hyphae (mycelium) grow? 
Describe the nature of the surface of the fly's 
body. How can the deHcate mycelia penetrate to 
the interior of the fly? 

3. Upon what does this fungus feed? State in detail 
the necessary steps in the process of getting this food 
into the interior of the mycelium. In this coAnec- 
tion make comparisons with Phycomyces (see F, 4, 
xinditr Phycomyces, p. 125). 

4. Is there any correlation here between the absence of 
chlorophyll and the habitat of the plant? If so, 
explain, and compare with Phycomyces and with 
Spirogyra. 



SAPROLEGNIA I 2 9 

F. Asexual Reproduction: 

1. Carefully study again the terminal sporangia. 
How many times longer than broad are they? 
Compare the thickness of the sporangium walls 
with those of the remainder of the hyphae. Can 
you detect any variations in the thickness of the 
sporangium walls? If so, describe and explain. 
Describe and account for the shape of the free tip 
of the sporangium. 

2. Describe the shape of the zoospores, or swarm- 
Spores; their size; number in one sporangium; 
color. Are they all alike in these characters? 

3. Endeavor to find swarm-spores escaping from a 
sporangium. Do they merely float away, or have 
they power of locomotion? Look for organs of 
locomotion? If you find them, describe their 
number, length, action, and general appearance. 
Do they precede or follow the zoospore as it moves 
through the water? 

4. Do the zoospores ever move up or down through 
the water so as to be out of focus? If so, consider 
thoughtfully the thickness of the film of water 
in which they are, and try to form some conception 
of the size of a body that can move vertically 
beyond the range of vision in a film so thin. Briefly 
discuss this point. 

5. Do you see any evidence that any two of these 
swarm-spores are in the process of fusion? Do 
their movements appear to be directed, or not? 

6. Make suitable drawings to illustrate all points 
observed under F. 

G. Sexual Reproduction: 

I. Under suitable conditions female reproductive 
organs, oogonia, develop on certain hyphae near the 



130 MORPHOLOGY AND LIFE HISTORY 

body of the fly, and each oogonium develops a 
number of eggs. If oogonia are found, describe 
them carefully as directed above (F, i) for sporangia, 
making suitable drawings. Do they always occur 
at the end of the h3^ha that bears them? 
2. The male reproductive organs are antheridial fila- 
ments, growing either below the oogonia or on 
adjacent hyphae.^ They are of smaller diameter 
then the hyphae. If you find these organs, care- 
fully describe their appearance, contents, size, and 
relation to the oogonia. Illustrate all points ob- 
served with suitable drawings. 
H. General Questions: 

1. Do you find a physiological division of labor in 
Saprolegnia? If so, describe in detail. 

2. State why you consider this plant higher or lower in 
the scale of life than Phycomyces or Fucus. 

3. Describe all methods of dissemination of Saprolegnia 
that you can think of. 

^The development of the egg-cell without fertilization (i.e., by par- 
thenogenesis) is more usual than fertilization in Saprolegnia, so that fer- 
tilization, or even antheridial filaments, may be wanting. 




Albugo Candida^ (Blister blight) 

A. Classification: 
Division I. Thallophyta. 

Subdivision II. Fungi. 
Class V. Phycomycetes. 
Order. Peronosporales. 
Family. Peronosporaceae. 
Genus. Albugo. 
Species. Candida (Pers.) Roussel. 

B. Habitat: 

This fungus is parasitic on plants belonging to the 
mustard family (Crucif erae) . It tauses the ' ' blister - 
bKght," or "white rust," on the leaves and stems 
of the shepherd's purse (Capsella bursa-pastoris) 
and often on the radish. 

C. Naked-eye Characters: 

1. Describe the appearance (color, shape, size, etc.) 
of the bHsters formed by this parasite on the host- 
plant. What organs of the host are affected? 

2. Make drawings, natural size, showing all the 
features observed. 

D. Microscopic Characters: 

1. Study cross-sections of the host-plant taken through 
• one of the blisters. 

2. What causes the blisters? In what tissue or tissues 
of the host does the mycelium grow? 

. Nutrition and Growth: 
I. In what form must carbon be supplied to this plant? 
Why? 

1 Cystopus Candidas (Pers.) Lev. 

131 



132 MORPHOLOGY AND LIFE HISTORY 

2. In thin sections look for absorbing organs (haus- 
toria), branching from the mycelium and penetrating 
through the cell- walls into the cells. ^ Describe 
their relative length, shape and general appearance. 
How far do they project into the cells? What do 
you infer is the function of these organs? Suggest 
a way in which they might be able to pierce 
the cell-wall. What other function must they per- 
form besides the one you have already mentioned? 

3. Where and how does this plant digest its food? 
What foods does it need? What is their source? 

4. Is there any correlation between the absence of 
chlorophyll and the habitat of this plant? Explain, 
and compare with Phycomyces and Marchantia. 

5. Make a drawing showing three cells of the host, 
with the adjacent mycelium and the penetrating 
haustoria. 

F. Asexual Reproduction: 

1. Observe the chains of spores (conidia, or conidio- 
spores). On what are they borne? Describe their 
shape, color, size. Are they all of the same size? 
Which is the youngest conidium in a chain? Why 
do you think so ? Of how many cells is each conidium 
composed? Are they attached to each other? If 
so, how? 

2. Observe the conidia-bearing hyphas (conidiophores) . 
Describe their shape, and the appearance of their 
contents. Do they have cross- walls? .Observe 
this last point carefully, and describe. 

3. Describe in detail, from your own observations, 
the method of formation of the conidia. 

1 The haustoria are difficult to identify, especially with poor sections 
and too much time should not be spent in trying to detect them. 



^. ALBUGO CANDIDA 1 33 

4. Make one drawing showing all points observed, 
including the tissues of both host and parasite. 

5. Make a second drawing of two conidiophores. 
showing the attached chains of conidia and the mode 
of formation of the latter. In this drawing make 
the conidia at least 5 mm. in diameter. 

6. Include in your notes at this point a brief descrip- 
tion of the germination of the conidia. (The infor- 
mation should, if possible, be obtained from 
material supphed by the instructor, otherwise from 
lecture or reading.) 

G. Sexual Reproduction: 

1. The sexual reproduction of Albugo generally occurs 
in other parts of the host-plant, and later in the 
season than the a sexual reproduction. The tissues 
of the host-plant containing the sexual organs of the 
parasite are generally enlarged (hypertrophied) and 
distorted. 

2. In the material given you observe the large spherical 
oogonium, containing a single oosphere or ^gg 
surrounded by the so-called periplasm or epiplasm. 
Is the oogonium sessile or stalked? 

Closely appressed to the oogonium at some point 
find the smaller antheridium. Describe its shape, 
and general appearance. Are its contents separated 
from those of the hypha by a cross-wall? 

4. How does the male gamete (sperm) pass through 
the oogonium -wall and periplasm to the egg? . 

5. If your material is suitable, observe and describe 
the mature fertilized egg (oosperm). After fertili- 
zation th^ periplasm becomes transformed into the 
wall of the oosperm. Note the exospore (of one 
layer), and the endospore of three layers. 



134 MORPHOLOGY AND LIFE HISTORY 

6. Make drawings showing all features observed un- 
der G. 
H. General Questions: 

1. Explain how Albugo is disseminated. 

2. What weather conditions would favor its dissemina- 
tion? 

3. The blight caused by Albugo is difficult to eradicate. 
What characteristic of the plant helps to explain 
this fact? 

4. Classify the phycomycetes you have studied as 
either Zygomycetes (Section i), orOomycetes (Sec- 
tion 2), and give a reason for your classification. 
Give the literal meaning of these two new terms. 



Exoascus deformans (Peach leaf-curl)^ 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 
Class IV. Ascomycetes (Sac Fungi). 
Order. Protodiscales. 
Family. Exoascaceae. 
Genus. Exoascus. 
Species, deformans (Berk.) Fuckel. 

B. Habitat: 

I. What varieties of peach trees are most affected by 
this common and frequently destructive disease? 
Does it deform any other part of the plant than the 
leaves? How does it injure the tree? 

C. Naked-eye Characters: 

I . What is the character of the diseased tissues ? What 
color are they? Draw and otherwise compare a 
healthy and a diseased leaf. Draw also a diseased 
twig, showing hypertrophied stem. 

D. Microscopic Characters: 

1. Make thin sections of diseased leaves or stems and 
examine. Draw some of the intercellular mycelium, 
as well as one or two of the asci.. 

2. How many spores in a mature ascus? Is there 
evidence of yeast-Kke budding of spores in the 
ascus? Are there any asexual spores formed? 
How is the infection spread? 

1 The directions for Exoascus, MicrosphaerUf and Ustilago (pp. 135- 
139) were prepared by Dr. E. W. Olive, Brooklyn Botanic Garden. 

135 



Microsphaera Alni Lii.-.c inizz".;, 

A. ClassificoHim: 
Dh-ision T. Thallophyta. 

Sbii'sinE FimgL 

C:-5 IV. A5::-7cetes 'Sac Fund"'. 

Gei^us. ::;';>;::-'.::-^:. 
Sleeps .^ ; \Vallr.) WinL 

B. EabUuU 

I . Examine the spedmens available, and record what 
kinds of trees and other plants are affected by this 
common fungous disease. What is the significance 
of the specific name Alni? 

C. Nakedreye Characters: 

1. What causes the dusty or "mildewed" appearance 
of the infected leaves? Are both sides of the leaf 
affected? Describe the distribution of the infec- 
tion over the leaf-surface. 

2. WLi: are the minute yellowish or blackish bodies 
seen aning the white threads? Make a drawing 
{natural size' to illustrate your observations. 

D. Microscop:: Chzracters: 

I. Scrape cz 5:n:e of the whitish fungous threads 
(the mycelium , and examine with low and high 
powers. 5:::^ n :ne epidermis and try to find the 
sucker-like r^-ns haustoria "uiich grow down into 
the epidermis an I a :s :b nourishment. Dr an- 
them, if found. 

'See footnote, p. 135. 

136 



MICROSPHAERA ALNI 137 

In younger material, study the conidiospores, 
arising from upright hyphae (conidiophores) . Draw. 
How are the conidiospores formed, and what is 
their function? 

In older material, scrape off some of the black fruit- 
ing bodies (perithecia) and study. Draw one of 
the peculiar appendages. What is the function 
of the appendages? Crush a perithecium and 
study the contained sacs (asci) and ascospores. 
How many asci in each perithecium? How many 
ascospores in each ascus? Draw to show these 
points. 

What is the function of the ascospore? How are 
the perithecia formed; the ascospores? Of what 
economic importance are the mildews? 



Ustilago Zeae (Corn smut)^ 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 

Class V. Basidiomycetes (Basidium fungi). 
Order. Ustilaginales. 
Family. Ustilaginaceae. 
Genus. Ustilago. 
Species. ZecB (Beckm.) Ung. 

B. Habitat: 

I. Upon what part or parts of the corn plant is the 
smut found? Does it differ in this respect from 
smut on wheat, oat, and other common grains? 
If so, how? 

C. Naked-eye Characters: 

1. Describe the appearance of the host as affected by 
the parasite. Cut into both young and old smutted 
areas and describe the appearance of the infected 
regions. 

2. Draw, to show the part of the host plant infected, 
and the degree of enlargement of the smutted tis- 
sues as compared with the normal. 

D. Microscopic Characters: 

1. With scalpel or forceps remove some of the spores 
(often called "chlamydospores") from a smut-boil, 
mount, and study with both low and high powers. 

2. Draw, to show the shape and surface markings of 
the spores. 

3. If the spores are of the proper degree of maturity, 
they can be germinated on the surface of water, 

^See footnote, p. 135. 

138 



USTILAGO ZEiE 139 

or on a hard manure-extract agar surface. If such 
viable . spores are available, draw the germinating 
spore, showing the germ- tube, orbasidium (promycel- 
ium), and attached basidiospores (sporidia). How 
many cells to the basidium, and how many basidio- 
spores to each? 

4. What is the function of the chlamydospore? Of 
the basidiospore? 

5. From your reading, or otherwise, record how the 
corn-smut disease survives the winter, and how it 
is spread, as well as the amount of damage it may do. 

6. Compare the corn smut with the wheat smut as 
to the character of the lesions, the method of infec- 
tion, and the methods of control. 



Agaricus campestris (Meadow-mushroom)^ 

A. Classification: 
Division I. Thallophyta. 

Subdivision B. Fungi. 
Class V. Basidiomycetes. 
Series. Eubasidiomycetes (true or typical Basi- 
diomycetes. 

Sub-class. Hymenomycetes. 
Order. Agaricales. 
Family. Agaricaceae. 
Genus. Agaricus. 

Species, campestris L. 

B. Habitat: 

I. From your own observation, and from the class 
discussion and assigned readings, describe the 
habitat of this plant. 

C. Naked-eye Characters: 

1. Form. — Describe the form of your specimen. If 
specimens of different ages are available, compare 
their forms, and describe any variations in specimens 
of various ages. Is the form of the mature speci- 
mens constant? Is their size constant? 

2. Color. — Describe accurately, noting especially any 
variations in color. 

3. Structure. — Note the differentiation of the plant- 
body (thallus) into an expanded portion (pileus), 

^ The outline for the study of a fleshy fungus has been prepared with 
special reference to the meadow mushroom {A garicus campestris) . It is 
general enough, however, with the exception of the outline of classifica- 
tion, to apply to any gill-bearing form. Indicate in your notes the 
exact genus and species given you for study. 

140 



AGARICUS CAMPESTRIS I4I 

borne on a stalk, or stipe. Is there a ring of tissue 
(annulus) around the upper part of the stipe? 

(a) The pileus. Describe the shape, size, color, 
and any characteristic markings on its upper 
surface. Examine carefully and describe the 
margin of the pileus. Are there any charac- 
teristic elevations or depressions on the pileus? 
If so, state how many and where they are. 
Compare the color of the under surface in young 
and old specimens. 

Describe the shape, arrangement, relative 
number and color of the lamellae, or gills. 
Are the margins (free edges) of the gills entire 
or notched? Do they extend clear to the stipe? 
Are they attached to the latter? Do they all 
extend clear to the margin of the pileus? 
Describe any variations in size. Count the 
gills in a space of lo mm., then calculate from 
the circumference of the pileus the total number 
of gills. 

(b) The stipe. Describe its shape, and color, and 
any variations in color and diameter. Describe 
its mode of attachment to the pileus. De- 
scribe the method of attachment of the plant 
to the substratum. Is there a mycelium or 
other special means of fixation? If so, is it 
continuous with the tissues of the stipe? 

(c) The amitilus. If an annulus is present, de- 
scribe its location on the stipe; its structure. 
Compare its structure with that of the mem- 
brane on the edge of the pileus. What is the 
relation between the membrane and the annulus 
in young specimens? When these structures 
are united they form a veil. Is a veil present 



142 MORPHOLOGY AND LIFE HISTORY 

^ in young specimens examined by you? What 
do the annulus and marginal membrane repre- 
sent? 

{d) Make drawings, not less than life size, of both a 
young and a mature specimen, as seen from the 
side, labeling all parts. 

{e) With a sharp scalpel or razor carefully divide 
your specimen longitudinally through the 
middle, and make a drawing illustrating all 
features shown in longitudinal sectional view. 

(/) Make a third drawing showing the structure 
and outline of the stipe as seen in cross-section, 
and a fourth drawing, showing the outline of the 
gill as seen in cross-section. 
D. Microscopic Characters: 

1. When suitable material is available, note and de- 
scribe the mycelium, extending through the soil. 

2. The annulus and stipe. Mount (in clearing fluid 
or water) thin longitudinal sections passing through 
the stipe. Is the stipe composed of distinct tissues, 
e.g. J like the hypocotyl of Ricinus, or the thallus of 
Fucus? If so, describe. Observe that the stipe is 
composed of hyphae. Of what is the annulus 
composed, and what is its relation to the tissue of 
the stipe? Do the hyphae have cross-walls or 
septa? If so, what angle do the septa make with 
the walls of the hyphae? Do the hyphae branch? 

Do you find spaces between the hyphae? If 
so, describe their size and distribution. Make a 
drawing to show the features observed under 2. 

3. The pileus. Mount (in clearing fluid) a thin longi- 
tudinal section passing through the stipe, pileus, and 
a portion of a gill. Examine under low power. 
Can you trace the hyphae of the stipe into the pileus? 



AGARICUS CAMPESTRIS I43 

If SO, describe their arrangement within the 

pileus. Do they extend into the gills? 
4. Make a diagram, life size, to illustrate the relation 

to each other of the hyphae of the mycelium, stipe, 

annulus, pileus, and gills. 
Reproduction: 

1. Mount (in clearing fluid or water) thin cross-sec- 
tions of a gill. 

2. Observe the differentiation of the gill into a central 
tissue or trama, an outer, spore-bearing tissue, or 
hymenial layer (hymenium), and, between these 
two, a sub-h3mieiiial layer. Of what are these 
tissues composed? How are they distinguished 
from each other? Show by diagram the position 
of these three layers. 

3. The hymeniiun. Using a prepared slide, state the 
direction of its cells relative to the surface of the 
gill. Distinguish in it two kinds of cells, {a) club- 
shaped ones, paraphyses; {h) basidia (sing., basid- 
ium), bearing sterigmata (sing., sterigma). How 
many sterigmata terminate each basidium? Ob- 
serve the spores, borne on the basidia and hence 
called basidiospores. Are the basidiospores all of 
the same size? Explain. Describe their color, 
shape, surface markings (if any), and the number of 
cells of which they are composed. Is the color of 
the spores constant? To what is the color of the 
gills due? 

4. If a pileus with the stipe removed is placed with 
the gills down over a clean, smooth piece of paper 
(black or white according to the species used), then 
covered with a tumbler or other suitable glass 
dish, and left over night, a print of the spores, as 
they fell from the gills, will be found on the paper 



144 MORPHOLOGY AND LIFE HISTORY 

in the morning. Study a spore-print of this species, 
describe it fully, and state how it was formed. 

5. Make accurate drawings showing all features ob- 
served under E, 2 and 3. 

6. Sexual reproduction is unknown among the Agari- 
cales. 

7. Diagram the life history of the species studied. 

F. Nutrition and Growth: 

1. Could the mushroom exist independently of other 
plants? Consider this question thoughtfully and 
answer as fully as possible in a well-worded para- 
graph. 

2. Suggest an explanation for the rapid growth of 
mushrooms. 

G. General Questions: 

1. State whether there is a division of physiological 
labor in this plant, and, if so, to what extent. 

2. In what ways may this plant become widely 
distributed? 

3. State, with reasons, whether you consider the mush- 
room a more or less highly developed plant than 
{a) Spirogyra; (b) Polypodium. 



Puccinia graminis (Wheat rust) 

A. Classification: 

Division I. Thallophyta. 
Subdivision B. Fungi. 
Class V. Basidiomycetes. 
Series. Protobasidiomycetes (preliminary group 
of the series). 
Order. Uredinales. 
Family. Uredinaceae. 
Genus. Puccinia. 
Species, graminis Pers. 

B. Habitat: 

1. Examine the specimens exhibited in the laboratory, 
and state what plants are infested with this parasite. 
What is the significance of its specific name 
{graminis) ? 

2. Puccinia graminis requires two different kinds of 
hosts in order to complete its life history. One of 
these is the barberry {Berheris). The barberry- 
stage, however, is not absolutely essential, for in 
certain regions, e.g., Australia, the Central Western 
States, and California, where the barberry does not 
naturally grow, this stage may be omitted, the 
fungus being perhaps carried over the winter season 
on winter wheat, or possibly by mycelium in 
grain, or even by urediniospores. 

^ciAL Stage (on Berheris) 

C. Naked-eye Characters: 

I. Study the infected leaf of the barberry. On its 
under surface observe the cluster-cups or aecia 
(sing., (Bcium). 

10 145 



146 MORPHOLOGY AND LIFE HISTORY 

2. On the upper surface observe the small dots, the 
pycnia (pycnidia, or spermatia). What is their 
color? Their shape? What relation does their 
position bear to that of the ascia? 

3. Study both aecia and pycnia with the aid of a hand 
lens. Describe carefully the appearance of the 
infected areas. 

4. Make a drawing, Hfe size, of the barberry leaf, show- 
ing the features under C, 1-3. 

D. Microscopic Characters: 

1. Study longitudinal sections through an aecium, 
using low power. 

2. How are the infested tissues of the host affected by 
the parasite? 

3. Note the aeciospores. Describe their shape. Are 
they all of the same size and shape ? How are they 
produced? What is the cause of the cluster-cups 
that appear on the leaf -surf ace? 

4. Make out all you can of the details of the mycelia, 
and their relation to the cells of the host-plant, and 
describe. 

5. Make a drawing of two aecia in different stages of 
development, one before the epidermis of the leaf 
has been ruptured. Make the aecium at least 
30 mm. in longest dimension. 

6. Make a study, similar to that outlined in D, 1-5, 
of the pycnia, as seen in longitudinal section. Ob- 
serve the slender threads and the minute spermatia. 

7. What is the function of the aeciospore? Of the 
pycma? 

Uredo-stage (on Wheat, Triticum vulgare) 

E. Naked-eye Characters: 

I. Study the diseased spots on the leaves of the wheat. 



PUCCINIA GRAMINIS 147 

Use the hand lens, if necessary, to make out the 
features clearly. 

2. Is the shape of the spots (sori, sing., sorus) uniform 
and characteristic ? 

3. State their color. 

F. Microscopic Characters: 

1. Study longitudinal sections, through a uredo-sorus. 
If the material is not fresh, remove some of the 
contents of the sorus with a needle, and mount in 
water. Study under high power. 

2. Describe the color, shape, and relative size of the 
cells. Are there any surface marks? Do you find 
any remnants of the pedicel to which theuredinio- 
spore (''summer spore") was attached? What can 
you say of the thickness of the cell- wall? 

3. Of how many cells is the urediniospore composed? 

4. Make careful drawings of two or three uredinio- 
spores, at least 15 mm. in longest measure. 

5. State the function of the urediniospore. 

Telial Stage (on Wheat) 

G. Naked-eye Characters: 

I. Study the telial sori, as directed under E, above. 
Describe the order of their distribution. 
H. Microscopic Characters: 

1. Study as directed under F, above. 

2. Include in your notes, at this point, a description 
of the germination of the teliospore (teleutospore) . 
What is its function? State the function of the 
basidium (promycelium), and of the "spring spores," 
or basidiospores (sporidia). 

/. General Questions: 

I. What features seem to you to make this parasite 
easily distributed, and difficult to eradicate? 



148 MOEPHOLOGY AND UFE HISTORY 

2. St^te -z!:^: rris r? h ether vou would considei 
P: : : grat/unis jiigiier or lower in the scale of 
xiie L^iii VaucJseria (or Fucus), and Albugo (or 
Mucor), 

3. \\ :i : c ::. brief siimmaiy of the fife history of Fucdma 
graminis, and devise a diagram to illustrate this. 

Note 

::: the irscriiiing order, iroi:: -i:^^r: :: -:~ e: ::: :::e sca'e. 

VVc now icCum to the iciiis, tQK".-"-r 1^6 (^uiii-woit 
(/5«»f<'5^, illustrating the Eusporangiat e 

The systematic relationship of the Isoeiice.c is doubt- 
ful On the basis of certain structural features of the 
g^rue: phyte {e.g., the structure of the archegiru.^ and 
the pssrssion of niu-tidliate sperms), some botanists 
class them with the Pterii hvt:,. On the the: h:^ni. 
some features of the anatomy of the sporophyte {fi.g., the 
possession of a liguU on the sporophyll) suggests that 
they are more dosely related to Sdaginella (Lepido- 
phyta). 



Isoetes (Quill wort) 

A. Classification: 

Division III. Pteridophyta.^ 
Class I. Eusporangiatae. 
Order. Isoetales. 
Family. Isoetaceae. 
Genus. Isoetes. 

Species, (e.g.) lacustris L, 

B. Habitat: 

Some forms grow on the bottom of ponds, others in 
moist meadows, or on the margins of bodies of water. 

The Sporophyte 

C. Naked-eye Characters: 

1 . General Features. 

(a) Note the differentiation of the plant into root 
and shoot, and of the shoot into stem and leaf. 

(b) Make a sketch, natural size, showing the 
general appearance of the entire plant. 

2. The Stem. 

(a) Without removing any of the leaves or roots, 
ascertain all you can about the shape, size, 
branching, and other characters of the stem, 
and describe. 

(b) With a sharp scalpel, make a cross-section of 
the stem through the middle, being careful not 
to remove any of the leaves or roots. 

(c) Describe the outline of the stem as seen in 

^See note, p. 148. 

149 



150 MORPHOLOGY AND LIFE HISTORY 

cross-section. Note the longitudinal furrows 

which give it a lobed appearance. 
{d) Are the roots attached to any special region of 
the stem? If so, describe. 

(e) Study the cross-section, identifying the central 
(vascular) cylinder, the epidermal layer, and, 
between the two, the fleshy tissue composed of 
several regions that are not distinguishable 
to the naked eye. 

(f) Make a drawing (X 3) sho'v\ing the outHne of 
the stem in cross-section, the tissue-regions 
observed, and the attachment of the roots. 

3. The Roots. 

(a) Describe the general appearance of a single root. 
Does it taper? Note that it is slightly fleshy. 
Are the branches forked at the tip (dichot- 
omous), or lateral? Dichotomous branching 
of roots is very rare. 

(b) Make a drawing (X 2) sho-^^dng these features. 

4. TJie Leaves. 

(a) CarefuUy remove one of the outer leaves at its 
point of attachment to the stem, first noting 
carefully which is its inner (ventral) surface, 
and which is its outer (dorsal) surface. 

(b) State whether the leaf is sessile or petiolate. 
The end by which it is attached is the leaf- 
base; the remainder of the leaf is called the 
lamina or blade. Note that the blade is 
subulate (awl-shaped). 

(c) Describe the exact length of the leaf in milli- 
meters. Observe the shght shallow groove or 
flattening. On which side of the leaf is it? 

(d) Hold the leaf up to the light and observe the 
single vascular bundle, surrounded by air 



ISOETES 



151 



chambers separated into compartments by 
numerous diaphragms. 
{e) Make a drawing (X 2) illustrating the features 
mentioned in 4, (c) and (d). 

(f) Make a cross-section of the blade near the 
middle, and note the number of air chambers 
surrounding the vascular bundle. 

(g) Make a diagram, 10 mm. in diameter, showing 
the leaf-structure in cross-section. 

(h) On plants which grow under water no stomata 
occur, but they are present on leaves that grow 
exposed to the air. Are stomata present in 
your specimen? If so, make a drawing of 
two or three, each 15 mm. in longest diameter. 

(i) Study carefully the expanded base of this leaf, 
noting the membranous margins. 

(k) Directly above the leaf-insertion, and on the 
ventral (inner) surface, observe the cavity or 
pit (fovea), containing the single sporangium. 

(/) Note the thin membrane (velum) extending 
over the sporangium. The velum is formed by 
the projection of the margin of the fovea. It is 
absent in some species, and in /. lacustris it 
does not completely cover the sporangium. 
In terrestrial species there is no opening through 
it. State the shape and location of this open- 
ing in your specimen, using a hand lens for the 
observation. 

{m) Above the fovea find a flat, membranous out- 
growth, the ligule. Describe its shape and 
state toward which end of the leaf it projects 
The slightly swollen base of the ligule is in- 
serted in a depression (foveola) , smaller than the 
fovea and directly above it. This last point is 



152 MORPHOLOGY AND LIFE HISTORY 

not easily made out except with the aid of a 
hand lens or microscope. 
(n) ]Make drawings as follows: 

(i) A leaf-base, 20 mm. at greatest breadth, 

showing all points observed under 4, 

(i)-(w). 

(2) A diagram, 40 mm. in greatest width, of an 
imaginary cross-section of the sporophyll, 
taken through the middle of the fovea. 

(3) A diagram, 15 mm. in greatest width, of 
an imaginary median longitudinal section 
through the base of a sporophyll. 

D. Asexual Reproduction : 

1. Note that some of the sporophylls bear large spores 
(megaspores) , and some small spores (microspores) . 
Study any constant differences (a) in structure, 
(b) in position on the stem, between the mega- 
sporophylls and themicrosporophylls. Define each 
of these terms. 

2. How many megaspores does a megasporangimn 
contain? 

3. IMeasure the diameter of a megaspore in millimeters. 
Study and describe its shape under the low power 
(mounted in water), noting any surface marks. 
Explain the presence of angles on the spore. 

4. Make a drawing of a megaspore, 20 mm. in diameter. 
Indicate the amount of enlargement. 

5. Study microspores under high power, describing 
their shape and surface marks. Draw two or three 
to the same scale as the drawing of the mega- 
spore. The number of microspores in each spor- 
angium in /. echinospora is said to be from 150,000 
to 300,000; of megaspores 150 to 300. 

6. Why is Isoetes a heterosporous pteridophyte? 



ISOETES 153 

Compare it with Polypodium vulgare in this 
respect. 

THE GAMETOPHYTE 

The germination of the spores and the development 
of the male gametophyte from the microspore, and of the 
female gametophyte from the megaspore, are very 
difficult to follow, and will be omitted here. The struc- 
tures of the gametophytes, and the process of sexual re- 
production should be carefully studied in a text-book, 
and demonstrated by the instructor, if material is available. 
E. Nutrition and Growth: 

1. Is the gametophyte at any stage dependent upon 
the sporophy te ? The sporophy te upon the gameto- 
phyte? (Consult a text-book.) 

2. It is important to remember that: 

(a) The microspore begins to germinate before it is 
set free, dividing into two cells, a large one and 
a small one. The smaller cell constitutes the 
entire vegetative portion of the male gameto- 
phyte. The larger cell develops into an an- 
theridium, consisting of four wall-cells, and four 
central cells. Each of the latter develops into 
a multiciliate, spirally coiled sperm, resembling 
those of the true ferns. 

(b) The megaspore begins to germinate after it is set 
free. It never develops chlorophyll-bearing 
tissues. In germination the nucleus divides 
into about 50 nuclei before any cells are formed. 
The cells begin to be organized about the 
nuclei, forming a small-celled tissue in the apex 
of the spore (where the three ridges meet), 
and a larger-celled tissue below. Archegonia 
then develop in the small-celled tissue, and the 



154 MORPHOLOGY AND LIFE HISTORY 

larger-celled tissue serves to nourish the young 
embryo-sporophyte, that develops from the 
fertilized egg. 

The archegonia are exposed for fertilization 
by the splitting of the wall of the megaspore 
along the ridges, but the prothallus itself does 
not project beyond the walls of the spore. 

When the sporophyte begins to develop from 

the fertilized egg, it continues to grow, without 

any resting period until it is mature. 

3. Diagram the life cycle oi Isoetes, as directed for the 

fern (I, 11, p. 78). Let MG = male gametophyte; 

FG = female gametophyte; s = sperm; e = egg; S 

= sporophyte; mi = microspore; mg = megaspore. 



^Equisettim (Horsetail) 

A. Classification: 

Division IV. Calamophyta. 
Class II. Equisetineae. 
Order. Equisetales. 
Family. Equisetaceae. 
Genus. Equisetum. 
Species, (e.g.) arvense L. 

B. Habitat: 

I. The field horsetail (E. arvense), is common along 
. railway embankments, roadsides, and fields. It 
apparently prefers north-facing slopes, and has a 
great tendency to become weedy. 

C. Naked-eye Characters: 
I. The Stem. 

(a) Using herbarium specimens or alcoholic material, 
if fresh material is not available, observe the 
underground stem (rhizome), and the upright 
aerial branches. 

(b) Of the latter, observe two kinds: (i) non-green, 
unbranched, bearing only scale-leaves, and 
terminating in a prominent strobilus or cone; 
(2) green and branched, also bearing scale- 
leaves, but no cone. 

(c) Which kind of aerial branch appears first above 
ground in the spring? What advantage may 

. this possess for the species? 

(d) Explain the physiological significance of the 
green color of the non-reproductive branches. 

15s 



156 MORPHOLOGY AND LIFE HISTORY 

Of what significance, in this connection, is their 
profuse branching? 

{e) Describe the surface of the stem along the 
internodes, noting the presence or absence of 
ridges, the hardness (or otherwise), and the 
"feel" of the surface. To what are the last 
two characters due? 

(/") If material of Equisetum hyemale (the *' scour- 
ing rush") is available, it will be instructive to 
burn a portion of the stem in a Bunsen flame, 
and to examine the unburned portion under 
a microscope. The preservation of the cell- 
walls, uninjured by the flame, is due to the 
fact that they are impregnated with silica, 
taken up by the plant from the soil in the 
form of a silicate, and secreted by the proto- 
plasm of each individual cell. It is the pres- 
ence of the silica that made this species useful 
for scouring cooking utensils, and thus gave it 
its common name. 

2. The Leaves. 

(a) Describe the shape and character of the leaves; 
their arrangement on the stem {i.e., opposite, 
alternate, or whorled). 

{b) Do the leaves function in the work of photo- 
synthesis? In what organ or organs is that 
function performed? 

(c) To what, in the fern, are the branches of the 
vegetative part of the stem analogous? To 
what are they homologous? To what, in the 
fern, are the scales at the nodes analogous? 
To what are they homologous? Explain. 

3. The Roots. 

(a) Briefly describe their character and distribu- 



EQUISETUM 157 

tion. Does their distribution on the rhizome 
bear any constant relation to the point of origin 
of the aerial branches? 
4. Make drawings showing all points observed under 

C, 1-3. 
D. Asexual Reproduction: 

1. Vegetative Propagation. 

(a) Describe the possibility of the multiplication 
of new individuals by the isolation of pieces of 
the rhizome. 

2. Reproduction by Spores. 

(a) Sketch the strobilus or cone (X 3). 

(b) Make a cross-section of the cone at about one- 
third of the distance from the apex, and observe 
the central axis, and the manner in which the 
sporangiophores are borne. 

(c) Carefully dissect off a sporangiophore, and ob- 
serve (i) its stalk; (2) its peltate (shield-like) 
top; (3) hanging from the under surface of 
the shield, the sporangia. How many spor- 
angia on each sporangiophore? Examine sev- 
eral sporangiophores to see if the number of 
sporangia is constant. Describe the dehiscence 
of the sporangia. 

(d) Examine the spores under the microscope. 
Can you detect more than one size; i.e., is 
Equisetum a homosporous or a heterosporous 
plant? 

(e) Describe the appendages (elaters), of the 
spores. How many on each spore? They are 
formed by a modification of the outer coat of 
the spore. Observe their behavior when 
breathed on at frequent intervals. 

(/) While the spores are morphologically homo- 



158 ' MORPHOLOGY AXD LIFE HISTORY 

sporouSj they give rise to dioecious gameto- 
phytes. Are they, therefore, physiologically 
alike? 

(g) Since the spores have different sex-value, some 
gi\'ing rise to antheridial, others to archegonial 
prothallia, suggest the advantage of the hygro- 
scopic elaters in tending to tangle up together 
several spores before they germinate. 

(h) Make draT\'ings illustrating all points observed 
under D, 2, (a)-{f). 

E. Sexual Reproductioft: 

1. It is not essential in an introductory course to 
study the gametophytes, and sexual reproduction 
of Equisetum in the laboratory, and it is seldom 
possible to secure suitable material in sufficient 
quantity for a large class. 

2. If material is abundant and time permits, the 
gametophytes may be studied, described, and 
sketched, noting especially color and general form, 
branching, rhizoids, archegonia, antheridia, and 
the dioecious habit. 

3. From prepared slides further details as to arche- 
gonia, antheridia, eggs, sperms, and fertilization 
may be studied, under the instructor's direction. 

F. Division of Physiological Labor: 

I. Write two or three paragraphs describing the 
di\'ision of physiological labor, (a) as between 
various vegetative processes, and {h) between the 
latter and reproductive processes. Give special 
attention in this to the work of each of the three 
kinds of branches. 

G. Life Cycle: 

I. Make a diagram, as pre\'iously for other forms, 
illustrating the life cycle of Equisetum. 



Lycopodium (Club-moss) 

A. Classification: 
Division V. Lepidophyta. 

Class I. Lycopodineae. 
Order. Lycopodiales. 
Family. Lycopodiaceae. 
Genus. Lycopodium. 
Species, (e.g., clavatum L.) 

B. Habitat: 

I. Nearly all the species of Lycopodium prefer moist 
situations. They are widely distributed over the 
earth, in both hemispheres, from the torrid to the 
frigid zones, and commonly grow in shady or partly 
shaded places. A few tropical species are epiphytic. 
They generally prefer a substratum rich in humus 
or other organic matter. 

THE SPOROPHYTE 

C. Naked-eye Characters: 

1. General Features. 

(a) Note whether, or not, the plant is differentiated 
into root and shoot, and the latter into stem 
and leaves. If the stem branches, briefly 
describe. 

2. The Stem. 

(a) Describe the attitude of the stem (e.g.j erect, 
f trailing). Does the tip of the stem turn up, 

or otherwise? 

159 



l6o MORPHOLOGY AND LIFE HISTORY 

(b) Describe the mode of branching. 

(c) Are there any speciaHzed {e.g., cone-bearing) 
branches? 

(d) Is there a terminal bud? Lateral, or axillary 
buds? 

3. The Roots. 

(a) Does the stem bear roots only at its posterior 
end, or otherwise? Describe. 

(b) Briefly characterize the roots. 

4. The Leaves. 

(a) State their manner of distribution on the stem. 

(b) Describe an individual leaf. 

5. Make dr.a wings as follows: (i) of a portion of the 
stem, to show mode of branching, distribution of 
leaves and roots, and other general features, natural 
size; (2) a leaf (X 5). 

D. Asexual Reproduction: 

1. Vegetative Propagation. 

{a) Describe the method of propagation by the 
annual apical growth of the stem. 

(b) Does the species you are studying in the 
laboratory possess buds or bulbils that may 
fall away, and develop into new plants? If so, 
describe their distribution on the stem; their 
relation to leaves, etc. 

2. Reproduction by Spores. 

(a) Describe the location of sporangia, especially 
their relation to leaves. Are they borne in the 
leaf -axils or on the leaf -surf ace? If the latter, 
on which surface? What relation do they bear 
to the leaf -base? Is there more than one 
sporangium to each leaf? 

(b) Are there special sporophylls? If so, how do 
they differ, in location and characteristics, 



LYCOPODIUM l6l 

from the foliage-leaves? Are they aggregated 
in a cone? If so, what effect does the forma- 
tion of the cone have on the further growth of 
the branch? 

(c) Is Lycopodium a homosporous or a heterosporous 
;. plant? 

{d) Describe a single sporangium, its mode of 
dehiscence, and the relative number {i.e., 
few or many) of spores it bears. 

(e) Into what do the spores develop? 

(/) Make drawings as follows: (i) acone (X 4); 
(2) a sporophyll, with sporangium (X 10); (3) 
under the low power a few of the spores, and 
(from younger sporangia) a few of the spore- 
tetrads. 

THE GAMETOPHYTE 

E. Sexual Reproduction: 

1. The gametophyte of Lycopodium is rarely seen, and 
not readily obtained in artificial culture. Its 
laboratory study may be omitted in a beginning 
course, but the subject should be presented by 
lecture, or preferably studied from a text and then 
discussed in class, with demonstrations of preserved 
material. 

2. Diagram the life cycle of Lycopodium. 



11 



Selaginella (Little club -moss) 

A. Classification: 

Division V. Lepidophyta. 
Class II. Lepidodendrineas. 
Order. Selaginellales. 
Family. SelagineUacese. 
Genus. Selaginella. 

Species, {e.g.) caulescens Spring (Syn. amoena 
Hort.) 

B. Habitat: 

I. Various species of Selaginella are common in cul- 
tivation in greenhouses. In nature they usually 
grow in moist situations, usually preferring shade. 

THE SPOROPHYTE 

C. Naked-eye Characters: 

1. General Features. 

{a) If possible, observe plants of various species 
growing in greenhouses, noting their general 
appearance and habit {e.g., erect, climbing, 
traiHng). 

2. The Stem. 

{a) By breaking off a small piece from the end of 
f| your specimen, ascertain whether the stem is 

I tough, brittle, fibrous, etc. 

{h) Describe the mode of branching {e.g., alternate, 
opposite, dichotomous (forked), etc.). Do the 
branches bear any relation to the leaves, e.g., 

are they in leaf-axils? 

162 



SELAGINELLA 1 63 

(c) Is the branch differentiated into regions? If 
so, briefly describe. 

(d) Does the branch show a tendency to be dorso- 
ventral? How do you determine this? 

(e) Do you note, in entire plants, any indications 
of response to gravity, moisture, or the direction 
of light? 

2. The Leaves. 

(a) Describe their position on the stem. Is the 
flat appearance of the stem due to the leaves 
being opposite, or to the attitude they have 
assumed as they mature. 

{b) Are the leaves differentiated into petiole, blade, 
etc.? 

{c) Describe any apparent adjustment or arrange- 
ment resulting in the most favorable illumina- 
tion of leaves. 

{d) Describe any variations in the color of the 
leaves, and endeavor to account for it. 

3. The Roots. 

(a) Is the plant rooted in the soil? 

(b) Do the roots branch? If so, describe. 

(c) Are there any other roots besides those in the 
soil? If so, describe them, and their location, 
and suggest any. advantage they may be to the 
plant. 

{d) Make drawings to illustrate all characters 
observed, including (i) a portion of the leafy 
branch (X 2) ; (2) a leaf (X 10) ; (3) aerial roots, 
if any. 
D. Microscopic Characters: 
I . The Leaf. 

(a) Mount an entire foliage-leaf in water or clear- 
ing fluid on a slide. Observe under the micro- 



164 MORPHOLOGY AND LIFE HISTORY 

scope, using low and high powers, and describe 
all details of leaf-structure thus brought out, 
including 

(b) The shape and arrangement of the cells; the 
color, size, and distribution of the plastids in 
the cells; any other cell contents; 

(c) Variations between marginal cells, those along 
the central axis, and those lying between. 
Account for any constant differences observed. 
Do you think any observed differences may be 
attributed to environment? Explain. 

(d) Can you identify a tiny, membranous flap, 
the ligule, near the leaf -base? On which side 
of the leaf (dorsal or ventral) is it? Be sure 
to examine both sides of the leaf in this connection. 

(e) Are there stoma ta? If so, describe their 
location. 

(/) Make drawings sufficiently large to illustrate 
all points observed under P, i. 
2. The Stem. 

(a) With the razor, make thin cross-sections of 
the stem, and mount them in water or clearing 
fluid. 

(b) Is the stem differentiated into (i) epidermis; 
(2) vascular regions; (3) fundamental tissue 
cortex) ? If so, describe. 

(c) Note the presence or absence of air-spaces. 
{d) Compare the tissue-system of the Selaginella 

stem with those in the fern, 
(e) Describe the distribution of xylem and phloem 

in the vascular bundle. . 
(/) Do you find indications of vascular bundles 

passing out to the leaves? 



SELAGINELLA 1 65 

{g) Draw a section of the stem (X 20), to illustrate 
2, {a)-{c). 
E. Asexual Reproduction: 

1. Vegetative Propagation. 

ia) Describe any means of vegetative propagation 
disclosed by your observations, already made. 

(b) If opportunity offers, the vegetative propaga- 
tion of Selaginella may be experimentally 
demonstrated in the greenhouse or Wardian 
case. 

2. Reproduction by Spores. 

(a) Observe the "cones." How are they dis- 
tinguished? Are they terminal on the main 
branches, or axillary? 

(6) Draw (X 5). 

(c) Place a small portion of a branch, bearing several 
mature cones, under a glass bell-jar, and after 
twenty-four to forty-eight hours observe the 
distance to which the spores have been projected. 
Note the two kinds, their relative number, and 
differences in color, etc. 

(d) Carefully remove sporophylls (i) from near the 
base of the cone; (2) from the middle or above, 
and mount in water or clearing fluid, keeping 
distinct, on separate slides, those from the two 
regions., 

(e) Note both megasporophylls, bearing mega- 
sporangia, and microsporophylls hearing micro- 
sporangia. How are they distinguished? 

(/") Are the sporangia inserted on the leaf, or on 
the stem in the axil of the leaf? Compare with 
the other plants studied in this respect. 

(g) Describe the structure of the walls of the 
sporangia. 



1 66 MORPHOLOGY AND LIFE HISTORY 

ih) Carefully count and record the number of 
megaspores in one megasporangium. Is the 
number aways even? 

ii) Carefully observe the megaspores under a high 
power, and endeavor to account for their shape. 

(j) Make drawings to show all points observed 
under £, 2, {a)-{h). 

(k) Make a study of the microsporophylls, micro- 
sporangia, and microspores, similar to those 
just made under E, 2, {a)-(j). 

(I) The number of microspores is too large to 
permit of their being readily counted. Sug- 
gest any advantage to the plant in such a large 
number of microspores. Explain the cause of 
the difference in size. Suggest an advantage 
to the plant in the large size of the megaspore. 

(m) Mount megaspores and microspores together 
and make drawings to show their relative 
sizes. 

(n) Make drawings to illustrate all points observed 
under E, 2, (k). 

F, Sexual Reproduction: 

I. The gametophytes of Selaginella are not readily 
obtained in suitable form for study. If prepared 
slides are available, studies may be made of: 
{a) Archegonia and eggs. 
{h) Antheridia and sperms. 

G. Comparisons: 

1. Compare the relative prominence of the gameto- 
phyte and sporophyte in Selaginella. Compare, 
in this respect, with all the forms previously studied. 

2. Compare the method of reproduction by spores in 
Selaginella with that in the forms previously 
studied. Why should Selaginella be considered 



SELAGINELLA 1 67 

either higher or lower in the scale of life than 
those forms? 
H. Life Cycle: 

I. Make a diagram to illustrate the life cycle of 
Selaginella. Briefly state differences between this 
life history and that of the fern, and of Anthoceros, 



Zamia floridana (A cycad) 

A. Classification: 

Dh-ision YI. Cycadophyta (The Cycads). 
Class II. Cycadineae (^Modern Cycads). 
Order. Cycadales. 
Family. Cycadaceae.^ 
Genus. Zamia. 
Species. Floridana DC. 

B. Habitat: 

I. Most of the Cycadales occur only within the tropics, 
but two genera. Zamia and Cycas, are also sub- 
tropical. Zamia occurs in the United States only 
in Florida, where it is rather common, and in Porto 
Rico. It is frequently cultivated in greenhouses. 

^'EGETATR'E ORGANS 

C. The Stejn: 

I. Briefly describe the stem, noting its general appear- 
ance, size, relation between its diameter and height, 
variations in diameter, character of the surface, its 
relation to the surface of the soil. Note the pres- 
ence or absence of branches. 

D. The Leaves: 

I. Describe their arrangement on the stem, the nature 
of the blade (entire, di\'ided. etc.), the color, and 

^By some botanists tlie genera Zamia, Macrozamia, and Dioon, having 
both staminate and carpellate cones, are assigned to a separate family 
(Zamiaceae), distinguished from the Cjcadaceae (in the narrower sense), 
which bear only the microsphorophj-lls in cones. 

i68 



%. ZAMIA FLORID ANA 1 69 

the presence or absence of a petiole. Describe 
accurately the vernation (condition in the bud), as 
shown by young leaves just unfolding. 

2. Suggest any advantage to the plant of any of the 
facts recorded under D, i. 

3. Compare the character of the leaves with that of 
any of the ferns. 

E. The Roots: 

I. Briefly state their location and functions. 

REPRODUCTIVE ORGANS 

F. The Staminate Cones: 

1. Describe their appearance, and, if the material is 
suitable, their distribution on the plant. 

2. Describe, accurately, the distribution of the micro- 
sporophylls (stamens) on the main axis, or stem, of 
the cone. 

3. Make drawings, natural size, showing {a) a surface 
view of the cone; (h) the cone as seen in longitudinal 
section. 

' 4. Remove one of the stamens. Describe it, and note 
the microsporangia (pollen-sacs) attached to its 
lower surface. Describe them, their number, dis- 
tribution, mode of attachment, and manner of 
opening (dehiscence). 

5. Make drawings {a) of a stamen with pollen-sacs 
attached; {h) of two or three pollen-sacs (X lo). 

6. The staminate cone is in reality a primitive flower. 
From this study, of what structure would you infer 
that flowers are a modification? 

G. The Male Gametophyte: 

I. The young pollen-grain (microspore) begins to 
germinate before it leaves the pollen-sac, two divi- 



lyo MORPHOLOGY AND LIFE HISTORY 

sions of its nucleus taking place. By the first cell- 
division two cells are formed, one, the first prothal- 
lial cell, representing the vegetative portion of the 
male prothallus; the second, or antheridial cell 
(called the ''antheridial initial" by some botanists), 
divides again, forming a tube -cell and a generative 
cell. By the division of the generative cell, the 
stalk-cell and body-cell are formed. The division 
of the body-cell gives rise to two sperm cells, 
and each of these latter becomes transformed 
into a motile sperm. 
2. Complete the following diagram of the above se- 
quence of cell-di\asions : 

Microspore 
O 



First Proth. ^ ^ Anth. CeU 

CeU 

3. !Mount several pollen-grains in water, and examine 
them under the high power. Describe their shape 
and contents. Draw. 

4. The study of the mature male prothallus, produced 
by the formation of a pollen-tube, -^dll be omitted 
here. 

B.. The Young Car pell ate Cone: 

1. The youngest cones offered for study were collected 
about March i. 

2. Describe the cone, and the distribution of the mega- 
sporophylls (carpels) on its main axis, or stem. 
Draw, natural size. 

3. Carefully dissect^ off one of the carpels. Describe 

ipor economy of material, with large classes, excised carpels may be 
supplied. 



^. ZAMIA FLORID ANA 171 

its form and surface characters, and note the num- 
ber, and place and mode of attachment of the large 
megasporangia (ovules) . Note their color. Draw, 
natural size. 
4. Do you find smaller, undeveloped ovules? These 
have probably not been pollinated. 
/. The Young Ovule: 

1. Is the ovule enclosed by the carpel, or is it naked? 
State why Zamia is classed as a gymnosperm. 

2. At the end of the ovule, opposite its point of attach- 
ment, note the small, often slightly elevated, dark 
spot, which marks the place of the micropyle (small 
gateway), through which the pollen-grain passes 
in order to reach the pollen-chamber within. This 
process is called pollination. In Zamia, pollination 
occurs about Jan. i. 

3. Remove an ovule, carefully noting where and how 
it is attached to the carpel. 

4. Describe its surface and shape. How may the 
latter, in part, be accounted for? At the end 
opposite the micropyle observe the scar (hilum), 
where the ovule was attached. Draw.-^ 

5. With the scalpel, make a slight longitudinal incision 
of the integiunent (wall) of the ovule, being careful 
not to cut too deeply, so as to injure the delicate 
structures within. Describe the character of the 
tissue of the integument. 

6. The tissue next within the integument is the 
nucellus, or megasporangium. The integuments 
are outgrowths of the nucellus. 

^ Arrange all the drawings, showing the ovule at dififerent ages, serially, 
on a new sheet of drawing paper, so as to facilitate the comparison of the 
different stages, and to show at a glance the changes which the different 
parts undergo. 



172 MORPHOLOGY AND LIFE HISTORY 

7. After making a longitudinal incision, very carefully 
remove the nucellus, noting the greater thickness of 
the tissue at the micropylar end. This tissue serves 
as nourishment for the germinating pollen-grain. 

8. Within the nucellus is the globular young female 
gametophyte, or endosperm. Describe and (from 
your reading in the text-book) account for its 
consistency. 

9. With the razor make a median, longitudinal section 
of the entire ovule. Study and draw, naming all 
the parts. 

/. Older Stages in the Development of the Ovule: 

1. Examine ovules collected about April i, as directed 
under /. Compare their size with that of the 
younger ovules. Observe the fleshy texture being 
assumed by the outer portion of the tissue of the 
integument, and the differentiation of a harder 
inner layer (endopleiira) . 

2. Describe the changes which the nucellus has under- 
gone. Account for these changes. (The appear- 
ance of the nucellar tissue may be due, in part, to 
its disintegration by the growing pollen- tubes.) 

3. Remove the nucellus and describe the appearance 
of the endosperm. Note the slight depression in 
its micropylar end. What change has taken place 
in its consistency? Account for the change. 

4. With a scalpel cut away the endopleura, and then, 
with a razor, make a clean, median longitudinal 
section of the endosperm, and observe, imbedded 
in its micropylar end, two or more archegonia. 
These open into the depression, mentioned above, by 
a short neck, composed of only two cells. The short 
neck-canal may be seen if the section passes through 
a suitable plane. 



ZAMIA FLORIDANA 1 73 

5. With a hand lens observe the wall of the arche- 
gonium, and within, filling the venter, the large 
ovum, or egg. 

6. As outlined above (/, 1-4), examine and describe 
an ovule one month older (about May i), carefully 
noting the changes which the different parts have 
undergone. Observe especially the development 
of the hard inner layer of the integument. May 
this feature be of any advantage to the plant? 
If so, how? Does any of the nucellus remain? 
If so, describe. Note, in the depression of the endo- 
sperm, the openings into the archegonia. How many 
are there? Draw this depression as seen in end 
view. 

7. Construct a diagram of an ovule of this age as seen 
in median longitudinal section, carefully labeling 
all parts. 

8. Make a diagrammatic drawing of a cross-section of 
the same ovule passing through the venters of the 
archegonia. 

9. In ovules one month older (about June i) the sac- 
like proembryo may be seen, lining the walls of the 
venter of the archegonium, and, growing from its 
basal end into the tissue of the endosperm, the 
prominent suspensor, at the free end of which the 
embryo begins to develop. As the suspensor and 
embryo increase in size, a cavity is formed in the 
surrounding endosperm. This cavity results from 
the digestion of the endosperm tissue, which goes 
to nourish the growing embryo and suspensor. 
Suggest how this digestion and subsequent nutri- 
tion may be accomplished. 

10. Make a drawing of a median longitudinal section 
of the ovule at this stage. 



174 MORPHOLOGY AND LIFE HISTORY 

K, The Seed: 

1. The seed matures about July i. Study the struc- 
ture of a ripe seed, comparing it in every point with 
the structure of the unripe oa^uIc, as directed above 
(/, i-io). 

2. Note the soft, outer layer of the integument. 
Describe it. 

3. In cutting away the hard, shell-like inner layer 
(endopleuxa) be careful not to disturb the portion 
of the nucellus that fits like, a cap over the mycro- 
pylar end of the endosperm. Now carefully Kft 
this portion of the nucellus and observe the long, 
coiled suspensor attached to it, and (at its other 
end) to the projecting thick, round peg (hypocotyl) 
of the embryo. 

4. With the scalpel gradually remove one-half of the 
endosperm, until you expose the embryo (young 
sporophyte) imbedded in it. Is the embryo curved 
or straight? Is it now confined to the venter of 
the archegonium? 

5. Obsers'e that the h}^ocotyl bears fleshy seed-leaves 
(cotyledons). How many are there? Compare 
their lengths. 

6. Does more than one embryo come to maturity in 
any one seed? 

7. When the sporophyte of Zamia begins to develop, 
is its growth continuous to maturity, or does a 
period of rest intervene between two stages of 
growth? Compare Zamia with the fern, moss, and 
Selaginella in this respect. 

8. Define a seed, and state how it difl'ers from an 
unripe ovule, and from a spore. 

9. Suggest any advantage to the plant of the seed- 
habit. 



■* ZAMIA FLORID ANA 1 75 

L. Nutrition: 

1. Describe the relative ability of the mature sporo- 
phyte and the gametophyte to lead an independent 
existence. Is the gametophyte ever independent 
of the sporophyte? Does the sporophyte ever live 
parasitically on the gametophyte? 

2. Why does the embryo-sporophyte need a supply of 
food stored in the seed? 

3. Would it be of any special advantage to Zamia to 
have a well-developed male gametophyte? Why? 

4. At home write a detailed description of the changes 
undergone by a starch grain, formed in the leaf of 
a mature carpellate sporophyte, until it becomes 
part of the tissue of the embryo-sporophyte of the 
next sporophyte-generation. 

5. Make a diagrammatic outline (using words, not 
drawings) showing the life cycle of Zamia from 
sporophyte to sporophyte. 



Pinus Laricio (Austrian pine) 

A. Classification: 

Division VI. Spermatophyta (seed-bearing plants). 
Subdivision A. Gymnospermae (seeds not inclosed 
in an ovary). 
Class I. Pinoideae (pine-like plants). 
Order. Coniferales (cone-bearing plants) . 
Family. Pinaceae (pine family). 
Genus. Pinus (the pines). 

Species. Laricio var. austriaca Endl. 
(Austrian pine). 

B, Habitat: 

The Coniferales are widely distributed over the earth's 
surface, often forming extensive forests. The genus 
Pinus occurs in North America throughout Canada 
and the northern United States, from the Atlantic to 
the Pacific coasts. The white pine {Pinus Strohus) 
occurs from Canada south along the Alleghanies to 
Georgia, and west to Illinois and Iowa. The western 
yellow pine {P. ponderosa) extends south to western 
Nebraska, Texas, Mexico, and California. The long- 
leaved or '^ Georgia pine" (P. palustris) is found near 
the coast from Virginia to Florida, and Texas. The 
spruce-pine [P. echinata) also occurs as far south as 
Florida, and in Illinois, Kansas, and Texas. Consider- 
able forests of it are found in southern Missouri. The 
loblolly pine {P. tceda) extends along the coast from 
Delaware to Texas and north up the Mississippi 
Valley to Arkansas. Pinus Laricio is not native to the 
United States, but has been introduced into cultiva- 
tion, as has also P. sylvestris, the ''Scotch pine," of 

northern Europe, and other species. 

176 



PINUS 177 

Pine wood was formerly one of the most valuable and 
at the same time one of the cheapest of soft-wood 
timbers, but owing to an utter disregard of the prin- 
ciples of scientific forestry, it is now one of the scarcest 
and most expensive. Regions that were formerly 
extensively forested, and the center of a prosperous 
lumber industry, are now waste land, often occupied by 
tall stumps, and a source of no profit. It is not neces- 
sary to destroy the forests in order to obtain an abun- 
dant supply of lumber, provided only that the crop be 
harvested in accordance with scientific principles. 
The conservation of the forests is one of the most important 
economic problems confronting our country, and excellent 
opportunities are now offered for well-trained foresters. 

Vegetative Organs 

C The Stem: 

1. In Pinus the shoot, as usual, is composed of the 
stem and the leaves. The stem is divided into a 
main part, or trunk, and lateral branches. The 
entire portion of the shoot, except the trunk, is 
designated by foresters as the crown^ of the tree. 

2. The following observations (C, 3-10) of the stem 
as a whole are to be made out of doors, recorded 
at this place in the laboratory notes, and handed in 
at the next class period. 

3. Designate the type of the trunk as excurrent (i.e., 
extending, entire from the ground to the apex of the 
tree) or deliquescent (i.e., extending entire for only 
a short distance from the ground, and then sub- 
dividing into the numerous limbs and smaller 
branches of the crown^). 

^The use of the term crown in this sense is quite different from its 
older use by plant anatomists to designate the region (usually at or near 
the surface of the ground) where the root and shoot join. 
12 



178 MORPHOLOGY AND LIFE HISTORY 

4. Describe variations in the diameter of the trunk. 

5. Do 3'ou find prominent swellings (buttressing roots) 

at the base of the trunk? If so, suggest their 
possible advantage to the tree.^ 

6. Describe the outline of the crown as flat, conical, or 
cylindrical. 

7. Describe the -appearance of the bark. 

8. Note that the lateral branches appear to be given 
off in whorls, or circles, at regular intervals along 
the trunk. Observe closely and state whether 
these are true whorls {ix., the component branches 
in exactly the same horizontal plane), or pseudo- 
whorls {i.e., the branches not really in the same 
plane) . 

9. Do you find enlargements on the under side of the 
larger limbs at the base? Suggest any advantage 
this may be to the limb; the conditions resulting 
in their formation. 

10. Draw a diagram illustrating all points observed 
under C, 1-9. Make the trunk 15 dm. high. 
D. The Vegetative Branches: 

1. In specimens furnished, note the two" kinds of vege- 
tative branch: The main or ^'long" branch, bear- 
ing scale-like leaves, and, in the axils (upper angle 
made by the leaf with the branch that bears it) of 
these scales, the dwarf branches, bearing the foliage- 
leaves or pine "needles." In what does the long 
branch terminate? 

2. The Long Branch. 

(a) Describe the arrangement (spiral) and dis- 
tribution of the dwarf branches on the long ones. 
(5) Xote the rings of dry bud-scales or scale-scars 

^The conditions favoring the formation of buttresses should be dis- 
cussed in class. 



PINUS 179 

at intervals along the branch. The sections 
of the branch between these rings represent the 
amount of each year's growth in length. Ascer- 
tain the age of your specimen. 
{c) State several ways in which younger portions 
of the stem may be distinguished from older. 

(d) For how many years do the dwarf branches 
remain attached? The scales that subtend 
them? Observe the scars left by the fallen 
dwarf branches. 

(e) Illustrate by a drawing the features observed 
under D, 2, {a)~{d). 

(f) Measure and record the amount of each annual 
growth, in length. 

(g) Draw a horizontal line as many decimeters long 
' as your specimen is years old. Mark off the 

line into decimeter spaces, and at the end of each 
decimeter erect a perpendicular as many milli- 
meters high as the branch grew during the corre- 
sponding year. Connect the tops of these 
perpendiculars by a gently curving line, which 
will be the curve of annual growth in length 
for the period covered. 

(h) Suggest reasons for the observed differences in 
amount of annual growth; for the direction of 
growth taken by the branch at various times. 

(i) Make a diagram of a cross-sectional view of the 
branch, and describe the relative position of 
wood, pith, and bark. Does the bark contain 
any chlorophyll? If so, in what region is it 
found? 

The Dwarf Branch. 

(a) Do you find nodes and internodes, or any 
other evidence that these branches grow in 



l8o MORPHOLOGY AND LITE HISTORY 

length each year? Find evidence that they 
do not. 

(b) Compare the number of needles borne by each 
dwarf branch. Is the number constant? On 
what part of the branch are they borne? 

(c) Note the bud-scales, some of which form a 
sheath about the bases of the needles. 

4. The Foliage-leaves. 

(a) Describe their shape. Are they differentiated 
into petiole and blade? 

(b) Make a drawing, natural size, of an entire leaf, 
and a diagram (X 10^ of a cross-sectional x-iew. 

5. The Terminal Bud. 

(a) Describe its color, coverings (bud-scales) , 
and shape. Draw (X 3). 

(b) With the scalpel remove one of the bud-scales 
at its base. Describe and draw (X 5). 

(c) Now remove, one at a time, the remaining bud- 
scales, having care not to break or injure the 
tender inner tissues. 

(d) Describe the place and mode of attachment 
of the scales. 

(e) Explain how they are adapted, in structure and 
position, to protect the bud. From what do 
they protect it? 

(/) Describe the color of the inner tissues. Can 
Piniis form chlorophyll in the dark? Explain. 

{g) Make a dra^ang (X 5) of the bud after the 
scales have been removed. 

{h) With a sharp scalpel make a median longi- 
tudinal section of the bud. Observe the central, 
conical axis, bearing thiu membranous scales. 
In the axil of each scale find a small knob-like 
outgrowth. 



PINUS l8l 

(i) Make a drawing (X lo) of the longitudinal view. 
(k) Into what will the bud develop? What will 

become of each of its parts? 
(/) How much of your specimen represents last 

year's terminal bud? The bud of year before 

last? 
(m) When the annual growth of a branch ends with 

the formation of a bud the growth is called 

determinate. Is the growth of the dwarf 

branches determinate or indeterminate? Of 

the long branches? 
E. Homologies: 

1 . Organs which perform like functions are analogous 
to each other. Organs which correspond to each 
other structurally i.e., which have the same mor- 
phological value, are homologous. For example, 
the flat, chlorophyllous stems of cacti and the foliage 
leaves of the maple tree are analogous, for they both 
function as organs of photosynthesis; but they are 
not homologous, for one is a stem, the other a leaf. 
The bud-scales of Pinus and the pine ^^ needles" 
are homologous, i.e., from the standpoint of struc- 
tural value (morphological standpoint) they are 
both leaves. But they are not analogous, for, 
whereas the ^'needles" act as organs of photo- 
synthesis, the bud-scales do not, as they have no 
chlorophyll. 

2. One of the most important, and often most difficult, 
problems of morphology is correctly to interpret 
the structural value of an organ; in other words to 
recognize homologies; for any organ may be pro- 
foundly modified, and appear so disguised as to 
make it extremely difficult to recognize its morpho- 
logical significance. Pinus furnishes an excellent 



1 82 MORPHOLOGY AND LIFE HISTORY 

illustration of the modification of organs for various 
functions. 
3. Enumerate all the homologs of the foliage-leaf 
found thus far on Finus, and show why the organs 
you name are homologous. 

Reproduction 

F. The Staminate Cone: 

1. On which portion of the vegetative branch are the 
staminate cones borne? Do they extend clear to 
the tip of the branch, i.e., are they ever terminal? 
In what does the tip of the branch that bears 
them terminate? Ascertain their length and 
greatest diameter in millimeters. 

2. Are the cones subtended by {i.e., borne in the axil 
of) a scale-like leaf? Note whether they are sessile 
or stalked? 

3. Observe the spiral-like arrangement of the micro- 
sporophylls of the cone. 

4. The staminate cones are modified branches. To 
which of the vegetative branches are they homolo- 
gous? 

5. Make a diagram (X2) showing the mode of attach- 
ment of the cone and the subtending scale. 

6. With a razor bisect a cone longitudinally and ob- 
serve the central axis, bearing the microsporophylls, 
or stamens. 

7. With the aid of a hand lens, or dissecting micro- 
scope, observe the short stalk of each stamen and, 
on the under (dorsal) side of the broadened stalk, 
two small pouches, the pollen-sacs (microspor- 
angia), containing pollen-grains. 



PINUS 183 

8. Make a diagram (.Xio) of the cone as seen in longi- 
tudinal section. 

9. Remove an entire stamen and observe that the 
tip of it is turned up so as to fit over the end of the 
stamen next above it. Suggest any advantage in 
this arrangement. 

10. Make a drawing to illustrate this feature. 

11. Make a cross-section of the stamen and ascertain 
of how many pollen-sacs it is composed. Draw. 
The pollen-sacs of ths stamen constitute the anther. 

12. The structure of the stamina te cone shows it to be 
in reality a simple flower. It is homologous to the 
stamina te flower of some of the higher plants. To 
what in Zamia is it homologous? 

G. The Young Male Gametophyte: 

1. Mount several mature pollen-grains in water and 
examine with the high power. 

2. Observe the body of the grain, and the two lateral 
wing-like expansions, developed from the outer coat 
of the pollen-grain. Suggest their use. 

3. Within the grain observe the tube-nucleus near the 
center, and the generative cell near the wall farthest 
from the wings. Look for the prothallial cell, 
which frequently may be seen between the wall of 
the grain and the generative cell. 

4. Make a drawing, 25 mm. broad, showing all features 
observed under G, 1-3. 

5. The nuclear and cell-divisions which give rise to 
these structures are steps in the germination of the 
microspore. Into what does the microspore of the 
heterosporus pteridophytes develop by germina- 
tion? To what, then, in Isoetes or Selaginella, is 
the mature pollen-grain of Pinus homologous ? 

6. If prepared microscopic slides are available, more 



184 MORPHOLOGY AXD LIFE HISTORY 

detailed study may be made of the structure of the 
pollen-grain. 
E. The Young Carpellate Cane: 

1. On which internode of the vegetative branch are 
the carpellate cones borne? On what part of the 
branch? Do they occur singly or in clusters? As 
terminal or as lateral outgrowths? 

2. Note that each carpellate cone is borne at the tip 
of a stalk. Describe any outgrowths on this stalk. 

3. Describe the attitude of the cone at the time of 
pollination, as erect or pendant. 

4. Observe the spiral arrangement of the cone-scales, 
somewhat more marked than in the staminate cone. 
In fresh specimens the cone-scales are sKghtly 
separated from each other at the time of pollina- 
tion. Explain the advantage of this. 

5. Make a drawing (X 2) of the cone with the stalk 
that bears it. 

6. Make a median longitudinal section of the cone and 
stalk, and represent by a drawing all parts seen. 

7. Carefully dissect off one of the central cone-scales, 
being sure to note which is the inner (ventral) and 
which the outer (dorsal) surface of the scale, and 
obser\dng the membranous bract which subtends it. 

S. On the inner surface of the scale, near the base, 
observe with the hand lens two ovules, each with 
two little prongs, between which is the pollen- 
chamber; between and above the OMiles a pointed 
outgrowth. 

9. Make drawings (X 10) of the o\aLliferous scale as 
seen {a) from the side; ih) from the outer surface, 
showing the bract; ic) from the inner surface, 
showing the ovules. 



> PINUS 185 

10. The ovules are megasporangia surrounded by a 
protecting integument. 

11. There is some evidence for considering the ovulif- 
erous scale and the bract that subtends it as a 
megasporophyll, or carpel. On the basis of this 
interpretation the bract would be homologous to the 
ligule in Isoetes or Selaginella. But other facts 
argue against this theory, and lead to different 
interpretations, so that the exact homology of the 
organ is in doubt. Possibly it represents two mega- 
sporophylls or carpels. If so, we must interpret the 
carpellate cone, not as a flower, like the staminate 
cone, but as inflorescence, or cluster of flowers, each 
scale representing a flower. 

/. The Mature Male Gametophyte: 

During the first spring pollination takes place, as 
described in the text-book, and the growth of the 
pollen-tube begins. Its growth is very slow, however, 
until the following spring, when the growth becomes 
more vigorous. The tube-nucleus passes to the tip of 
the pollen-tube, which penetrates the tissues of the 
nucellus (/, 6, p. 156), digesting a channel for itself as it 
grows, usually branching, and feeding on the digested 
tissue. The generative cell divides into a body-cell 
and a stalk-cell, and the nucleus of the body-cell 
again divides into two sperm-nuclei. 

K. The Female Gametophyte: 

Near the time of pollination the megaspore consists of 
one uninucleate cell (the one-celled stage of the embryo- 
sac). By repeated nuclear-divisions the nucleus of the 
megaspore gives rise to a large number of nuclei, which 
at first lie free in the surrounding cytoplasm; but later 
each of these nuclei organizes about itself a cell, 
surrounded by cell- walls. The tissue thus formed 



l86 MORPHOLOGY AND LITE HISTORY 

within the embryo-sac, and enlarged by growth, forms 
the young female gametophyte (endosperm). The 
megasporangium, surrounding the endosperm, is called 
the nucellus, as in Zamia, and both these structures are 
surrounded by a protecting envelope, the integument. 
The pollen-chamber lies between the tip of the nucellus 
and the integument. The micfopyle leads through 
the integument to the pollen-chamber. In the pol- 
lination of Pinus the entire pollen-grain passes into 
the pollen-chamber through the micropyle. 

L. The Ovule: 

The endosperm, nucellus, and integument together 
form the young o\aile. Nearly one year is required 
for its development to the stage described above. In 
the second spring, while the pollen- tube is rapidly 
elongating, and the nuclear divisions noted above are 
taking place within it, several archegonia develop in 
the micropylar end of the endosperm. In the venter 
of each archegonium lies the large egg. 

M. Fertilization: 

Eventually the pollen-tube enters the neck of an arche- 
gonium (compare with the process in Zamia and other 
Cycads), its contents are discharged into the venter, 
and one of the sperm-nuclei fuses with the nucleus of 
the tgg. Thus fertilization is accomplished, about one 
year after pollination. The transfer of the sperm- 
nucleus to the egg by means of a pollen-tube is called 
siphonogamy, and plants in which this occurs, 
Siphonogamia. 

The one-year-old cone, to be studied next,* represents 
the stage of development at about the time of fertiliza- 
tion. The sperms of Pinus are non-motile. 

N. The One-year-old Car peltate Cone: 

I . Compare the position on the branch, and the atti- 



■^ PINUS 187 

tude of the one-year-old cones with that of the cones 
at the time of pollination. 

2. Study these cones as directed above {H, i-ii), com- 
paring the older and the younger organs. En- 
deavor to explain any differences observed. 

3. Record the length and greatest diameter of the one- 
year-old cone, and make a drawing of it, natural 
size. 

O. The Two-year-old Carpellate Cone: 

1. Record, its position on the branch, its attitude, and 
dimensions. Compare it, in these points, with the 
young, and one-year-old cones. Draw, natural 
size. 

2. Make drawings of a detached scale as seen from 
{a) the outer (dorsal) surface, {h) the inner (ventral) 
surface, {c) the side. Describe any changes 
observed in the appearance and relation of the 
various points. 

3. Note that the ovule has developed into a winged 
seed. 

P. The Seed:^ 

1 . The seeds are usually shed from the pine cone during 
the third summer, about two years and a quarter 
after pollination. 

2. Record the dimensions, shape, and character of the 
surface of the seed. The small depression in the 
smaller end of the seed locates the micropyle, which 
is now grown together. Draw, natural size. 

3. Let fall from a height of several feet a seed of some 
species having wings still attached, and note the 
approximate time required to reach the ground. 
Remove the wing and repeat the observation. Sug- 

^ The large seeds of the nut-pine, Pinus edulis, or of Pinus pinea, may 
advantageously be used for this study. 



1 88 MORPHOLOGY AXD LIFE HISTORY 

gest a use of the wing. Is it ver}^ firmly attached 
to the seed? 

4. Remove the tough, outer seed-coat (testa), which is 
the mature integument, referred to ia jK^ and L 
(p. 185-186). The integument is analogous to an 
indusium , WTiv ? 

5. Underneath the testa, observe the thin, membra- 
nous inner seed-coat, formed by a separation and 
differentiation of an inner layer of the tissue of the in- 
tegument. Describe its color and surface-character 
as seen under the hand lens. Compare with Zaviia. 

6. Obsers^e the small hole through the micropylar end 
of the inner coat. "\Miat does this represent? 

7. Remove the inner seed-coat, ha\TQg care not to dis- 
turb the brownish, membranous cap on the micro- 
pylar end of the kernel. This cap is the remains 
of the nucellus (megasporangium) . Xote the modi- 
fication of its tissue at the place through which the 
pollen-tube passed on its way to the embr\'o-sac. 
The remainder of the nucellus was consumed by 
the female gametophyte duriag the development of 
the latter. 

8. "\Miat is the homology of the white, fleshy kernel 
of the pine seed. 

9. IMake a drawing (X 4) of the endosperm and nu- 
cellus. 

10. Remove the nucellar tissue. Is it firmly attached 
to the endosperm? Describe the appearance of the 
endosperm under the nuceUar cap. 

11. Ver\' cautiously separate the endosperm into longi- 
tudinal halves. Begin the dissection at the end 
opposite the micropylar end so as not to injure the 
embr3'o-sporophyte within. 

12. Observ'e that the embrj'o lies in a distinct ca\'ity or 



PINUS 189 

chamber, its tissues being quite distinct, anatomic- 
ally, from those of the gametophyte. Can you ac- 
count for the formation of this cavity? 

13. Note that the embryo is composed of a main axis, 
bearing a whorl of cotyledons borne near one end. 
Can you detect distinct regions of the axis? If so, 
how many, and how are they distinguished? How 
many cotyledons are there? Is the number always 
either odd or even? 

14. Observe that the embryo is attached at the end 
opposite the cotyledons to a slender filament, the 
suspensor. At this end of the embryo-chamber 
may frequently be seen the disorganized remains of 
other embryos that failed to develop. In rare 
instances two embryos develop in one seed. This 
is called polyembryony, a condition very common 
in lemons, and other citrous fruits. 

15. Make a drawing of the young sporophyte, 50 mm. 
long. 

16. Make a median longitudinal section of the embryo, 
and observe that the portion of the axis below the 
cotyledons (hypocotyl) is encased in an outer, 
strongly developed root-cap, which completely en- 
closes the hypocotyl. Note further that the coty- 
ledons are borne on the hypocotyl. From its op- 
posite end (radicle -end) the tap-root will develop. 
The hypocotyl is the first internode of the sporo- 
phyte. Where is the first node? 

17. At the summit of the axis, above the cotyledons and 
surrounded by them, observe the conical epicotyl. 
It will develop into the second and subsequent 
internodes. Explain the meaning of the term 
epicotyl. 

18. Construct three diagrams (X 5) showing (a) the 



I go MORPHOLOGY AXD LUE HISTORY 

entire seed in longitudinal section (the embryo not 
sectioned); {b) a cross-section of the seed, passing 
through the cot\'ledons and epicotyl; (c) a cross- 
section of the seed passing through the m'pocotyl. 
Q. The ''Germination'' of the Seed: 

1. Obser^*e specimens of seeds and seedlings represent- 
ing various stages of germination. 

2. Describe (a) the changes that the various parts of 
the seed undergo, in shape, size, and position; (6) 
the manner in which the seedling breaks through 
the surface of the soil, and the advantage of this; 
(c) the relative rate of early growth of the root and 
shoot, and the significance of this; {d) color-change 
in the cotyledons, its significance and whether or 
not it can take place in darkness; (e) the fate of the 
endosperm, and the e^ddent role of this tissue; (/") 
the manner of shedding the seed-coat; {g) the place 
of development and the character of any new organs. 
Draw. 

3. Compare the germination of a seed, with that of a 
spore. WTiat. in reaUty, is the germination of a 
seed? 

R. General Questians: 

1 . To which alternating generation does the pine tree 
belong? 

2. In a well-worded paragraph compare the relation 
of.gametophyte and sporophyte in the moss, fern, 
Isoetes (or Selaginella), and Pinus. 

3. State the relative prominence of the sexual and 
asexual generations in plant-groups of successively 
higher organization. 

4. When the young sporophyte oi Pinus begins growth 
does it grow continuously to maturity, or does a 



PINUS 191 

period of rest interyene? Compare it with Isoetes 
or Selaginella in this respect. 

5. What changes would result in the formation of a 
seed in Isoetes? What interferes with seed-forma- 
tion in that group? What changes would interfere 
with seed-formation in Finusf 

6. Define a seed. State several advantages to the 
plant of the seed-habit. 

7. To what, in the fern, is the endosperm of the pine 
seed homologous? To what in the moss? To 
what, in Isoetes or Selaginella, is the pollen-grain 
homologous? To what in the fern? State, with 
reasons, whether the leaves of the moss-plant are 
homologous or analogous (or neither) to pine nee- 
dles. In like manner, compare the organs of fixation 
of the moss-plant, of the fern-plant, of the fern- 
prothallus, and of the pine tree. 

8. Diagram the life cycle of Pinus as directed for 
Isoetes (E, 3, p. 154), substituting ^^( = pollen- 
grain) for MG{ = male gametophyte), and es{ = 
embryo-sac) for FG'( = female gametophyte). 



Trillium (Wake-robin) 

A. Classification: 

Division VII. Spermatophyta. 

Subdivision B. Angiospermae (seeds enclosed in an 
ovary) . 
Class I. Monocotyledoneae (embryo with one 
lateral cotyledon). 
Order. Liliales (lily order). 
Family. Liliaceae (lily family). 
Genus. Trillium. 

Species.^ (e.g.) sessile L. 

B. Habitat: 

All species of Trillium occur in the woods in early 
spring, and the genus has a geographic range extend- 
ing from Nova Scotia westward to Manitoba, and 
southward as far as Florida. 

1 Any species of Trillium may be used, with minor changes in the direc- 
tions; or, in fact, any other convenient genus of the Liliaceae. 

Note. — There are nearly 25,000 different species of Monocotyledons. 
The order of Liliales comprises about 5,000 species. The lower Mono- 
cotyledons have naked flowers {i.e., no sepals and petals), with the parts 
spirally arranged, as in the Gymnosperms. The higher ones have the 
parts of the flower arranged in concentric circles or cycles, five in number 
(pentacyclic), with usually three members in each cycle. Our knowledge 
of the monocotyledons is not yet adequate to make possible a satisfactory 
classification. Taxonomists differ in various points. The authors of 
Gray's "New Manual" (7th Edition, 1908) subdivide the Liliaceae into 
Tribes. Trillium is in the tribe Paridecs, Britton ("Manual of the 
Flora of the Northern States and Canada ") and others, divide the Liliaceae, 
as given in Gray, into four or more families, the trilliums being in the 
Convallariacece, or Lily-of-the- valley family. 

192 



> TRILLIUM 193 

C. The Shoot: 

1. General. 

(a) Note its division into a main, thickened under- 
ground part (rhizome), bearing numerous roots, 
and a long slender aerial branch. 

2. The Rhizome. 

(a) Describe its attitude (horizontal or erect), and 
its general appearance. Compare Trillium 
with the fern in this respect. 

(b) Are there branches, besides the aerial branch? 

(c) Note the thin membranous scales near the 
apical end. Record their number and position. 
Carefully remove them with the scalpel. What 
purpose may they serve? What is their 
homology? Make a drawing of one (X i). 

(d) Observe the nodes and intemodes. What 
do the nodes represent? Note the remnants of 
the old scales at each node.. Compare the 
lengths of the internodes. What is the mean- 
ing of this? 

(e) Describe any other scars on the rhizome. Are 
they on nodes or internodes? What do they 
represent? 

(/) What develops each year at the growing; end? 

(g) A plant that is continued indefinitely, from year 
to year, by means of a persistent root or stem, or 
both, is a perennial; one that persists for two 
years only, setting seed and dying at the end of 
the second season is a biennial, plants that set 
seed and perish at the end of one season are 
annuals. Name illustrations of each of these 
three classes of plants. 

{h) State, with reasons for your opinion, the age 
of your specimen. 

13 



194 MORPHOLOGY AND LIFE HISTORY 

3. The Aerial Branch. 

(a) Describe its general appearance, shape, length 
(compare several different specimens), color- 
ation (color-pattern), and presence or absence 
of branches. 

{h) At which end of the rhizome is it borne? Is 
it a terminal or a lateral outgrowth? Is it an 
axillary organ {i.e., borne in the axil of a leaf), 
, or not? On a node or an internode? 

{c) Make a drawing 20 mm. in diameter, showing 
the distribution of the fibro-vascular bundles 
as seen in cross-section. 

{d) What does the branch bear at its summit? 
Do you find any exceptions to this? 
D. The Roots: 

1. Describe their distribution on the root-stalk. Do 
they occur on both nodes and internodes? State 
the significance of the observed distribution. 

2. Record the presence or absence of branching. 

3. Compare the appearance of new roots with that 
of older ones. On what part of the rhizome are 
they borne? 

4. Describe the surface appearance of older roots. 
Remove a root 3 to 4 cm. long, hold it by each end? 
and gently pull (not hard enough to break the 
root). How does this affect the surface appear- 
ance? How do you think the original feature 
was produced? 

5. With the scalpel cut a root squarely off near its 
base and observe the cross-sectional view. Dis- 
tinguish three tissue-systems: {a) the epidermis; 
{h) the central cylinder; (c) between {a) and {h), 
the cortex. 



TRILLIUM 195 

6. Peel down a strip of the epidermis, and observe 
whether the wrinkling is confined to it or not. 

7. Make a drawing, twice natural size, showing the 
external features of the rhizome, together with a 
portion of the aerial branch, and roots. 

E. The Young Terminal Bud:^ 

1 . Carefully remove the aerial branch and surrounding 
scales and observe the terminal (apical) bud. 

2. Describe its color, shape, attitude, and the relation 
between it and the base of the aerial branch. Draw 
(X 2). 

F. The Mature Terminal Bud:'^ 

1. Use material gathered in late autumn, and care- 
fully dissect away the outer bud-scales. Identify 
the parts found within. 

2. Make careful drawings, and interpret the signifi- 
cance of this observation. 

G. The Foliage-lea'ues: 

1. Describe the number, location, and arrangement 
of the foliage-leaves. Are they petiolate or sessile? 

2. Observe: 

{a) The coloration (described, for T. sessile, as 

/^blotched''). 
{h) The outline of the base, apex, and margin. 
(c) The venation. 
H. The Flower: 

I. On what part of the shoot is it borne? Record 
the presence or absence of a flower-stalk (peduncle) . 
Explain the significance of the specific name of 
this species {T. sessile). Has the flower an odor? 
If so, describe it. 

1 On account of the large amount of material required, it is desirable 
to make E and F class demonstrations by the instructor. 



196 MORPHOLOGY AND LIFE HISTORY 

2. Observe: 

(a) The outer circle of parts (calyx) composed 
of separate sepals. How many sepals are 
there? Describe them as you did the leaves. 
Note. — The term calyx comes from the Greek 
word kalyx, a cup; the verb is kalypto, to 
cover. What organ of the moss has its name 
derived from the same source as calyx? 

(b) The circle of parts* (corolla) next within the 
calyx, composed of separate petals. How 
many petals? Are they opposite or alternate 
with the sepals? Record their color in fresh 
(not preserved) specimens. Describe a petal 
as you did the leaf and sepal. 

(c) With the corolla, a circle of three microsporo- 
phylls (stamens) each opposite a sepal. By 
carefully bending back (but not removing) 
the sepals and petals, observe whether or not 
the other stamens are in the same circle as 
the first ones, or in an inner (higher) circle. 
Describe their location with reference to the 
petals. Record the total number of stamens. 
Note that each stamen is composed of: 

(i) A stalk (filament), bearing at its tip, 

(2) An anther, composed of marginal, linear 
poUen-sacs (microsporangia), and connect- 
ing tissue (the connective). Observe 
whether the connective is prolonged 
beyond the sporangia. Note that the pol- 
len sacs dehisce (open) on the inside {i.e., 
are introrse). Describe their manner of 
dehiscence. 

(3) What do the pollen-sacs contain? De- 
scribe its color. 



TRILLIUM 197 

[d) The central pistil composed of: 

(i) The basal ovule-case (ovary). How many 

angles has it? How many lobes? 
(2) The relatively long styles. How many? 
Their inner surface is modified into 

(3) A stigma. Describe this stigma tic surface 
as seen both with unaided eye and under 
the low power. Usually, numerous pollen- 
grains may be seen adhering to it. What 

' process has therefore taken place? 

(4) The ovary is thus seen to be, not simple, 
but compound. It is composed of three 
carpels, bearing ovules. Since the ovules 
are megasporangia, what is the homology 
oithe carpels? 

Look up in the dictionary, and record at this point, 
the derivation of the names of the various parts of 
a flower, studied above. 

(a) It 'is important to note: (i) That the various 
cycles are each composed of the same number 
of parts; (2) that the parts of the various 
cycles alternate with each other. 

(b) When the other organs of a flower are inserted 
below the pistil they are said to be hypogynous. 
Is this true of Trillium? 

(c) The more or less enlarged end of the stem (or, 
in non-sessile forms, of the peduncle) on which 
the organs of the flower are inserted, is the 
receptacle. 

Make drawings as follows: 

(i) A sepal (X i); a^ petal (X i); a stamen (X 4) 
(both dorsal and ventral views); an imagined 
cross-section of an anther taken through the 



igS MORPHOLOGY AND LITE HISTORY 

middle (X4); the pistil (X 4); an imagined 
cross-section of the pistil (X 4). 
(2) A ground-plan of the flower, 5 cm. in diameter, 
first drawing five equidistant concentric cir- 
cles, and filling in the plan as directed by the 
instructor. 
(3) An imaginary longitudinal section of the flower 

(X2). 

5. Compare the length of the stamens with that of 
the pistil. Carefully consider and state the rela- 
tive probabilities of self-pollination and cross- 
pollination. 

/. Non-sexual Reproduction: 

I. Non-sexual reproduction in Trillium is confined to 
the growth of the persistent, underground rhizome. 
This organ is thick and fleshy, serving for the 
storage of food. 

K. Sexual Reproduction: 

1. Microspores. 

(a) Mount in clearing fluid (or water) on a slide 
some of the pollen from an anther. 

(b) Observe (first under low, then under high power) 
the individual pollen-grains. Describe their 
color and shape, and note the network of 
ridges on the surface of each. 

(c) By carefully focusing on individual grains there 
may readily be detected in some of them one 
nucleus, in others, two. Those in the one- 
nucleate stage are mature microspores. 

2. Male gametophyte. The division of the microspore- 
nucleus is the first stage in the germination of the 
spore. To what do microspores, when they ger- 



TRILLIUM 199 

minate, give rise? What, therefore, is the homol- 
ogy of the bi-nucleate pollen-grain? 

(a) The larger nucleus is the tube-nucleus, and 
presides over the development of the pollen- 
tube. The smaller is the generative nucleus. 

(b) Make drawings, 2 cm. in diameter, of a micro- 
spore and of a male gametophyte, labeling all 
parts. 

(c) After pollination, the formation of the pollen- 
tube takes place. This is usually spoken of as 
the ^'germination of the pollen-grain." 

The tube emerges through one of several weak 
places in the wall of the grain, grows down 
through the tissues of the style, digesting its 
channel as it proceeds, or, in some species, fol- 
lowing a canal already formed through the 
style. 

The generative cell (generative nucleus with its 
own protoplasm) follows down the pollen-tube, 
and divides into two non-motile sperm-cells. 
In some species, e.g., Samhucus (elder), this 
' division occurs before the tube develops. The 
pollen-tube passes through the micropyle, and 
discharges the sperm-cells near the egg. One 
of the sperm-nuclei fuses with the egg-nucleus, 
thus effecting fertilization. 

{d) For convenience in handling material the 
observation of the finer structure of the anther 
and pollen will be deferred until after the 
microscopic study of the ovary and ovules (3, 
below). 

Megasporophylls and Megasporangia. With a sharp 

scalpel or razor make a median cross-section of the 

ovary and observe: 



200 MORPHOLOGY AND LIFE HISTORY 

(a) Its outline. Each of the lobes represents the 
section of one of the carpels (megasporophylls), 
which together compose the tri-carpellate, 
compound ovary. 

(b) The number of compartments ("cells"). Do 
the septa (walls) that separate them meet in 
the center? Compare the number of cells with 
the number of carpels. 

(c) The placentse (sing., placenta), or surfaces of the 
septae to which are attached. 

(d) The ovules. Do the ovules he in a vertical or 
>L; in a horizontal plane? Are they few or numer- 
ous? In Trillium the ovules are borne on 
parietal placentae. 

(e) The funiculus (stalk) by which the ovule is 
attached to the placenta. Observe (using 
magnifier that the ovules have curved through 
1 80°, bringing their apical (micropylar) ends to 

2 their base or point of attachment to the fu- 

niculus. They are thus anatropous ovules. 

(/) Make a drawing, 4 cm. in diameter, showing 

the ovary (and ovules) as seen in cross-section. 

4. Histology of the anther. Development of the pollen. 

{a) Use prepared sHdes. The sections on these 
slides are triple-stained with safranin, gentian- 
violet, and orange. By this means the various 
parts of the cell are given diifferent colors, the 
cytoplasm a grayish tinge, the nucleolus and 
chromatin threads in the nucleus red, starch 
grains a deep blue. 

Using slides showing the microspore-mother-cell 
stage of Lilium canadense, or other convenient 
plant, 

(b) Observe the outline of the section as a whole. 



TRILLIUM 201 

(c) The central portion is the connective, contain- 
ing a vascular bundle. 

(d) Opposite the connective may often be seen a 
cross-section of the filament, with its vascular 
bundle. 

(e) The numerous, conspicuous blue-stained bodies 

are starch grains. 
(/) Note the epidermis, one cell thick. Does it 
cover the entire surface? Does it contain 
starch grains? Find numerous stomata, each 
with a small, underlying air-space. 

(g) At each side of the section will be seen two 
sporangia, containing the large microspore- 
mother-cells (pollen-mother-cells), with promi- 
nent nucleus. Observe the network of chrom- 
atin within each of these nuclei. The mother- 
cells adhere more or less closely, depending 
upon age. Their final separation from other 
cells, and from each other, marks the first 
separation of the gametophytic from the 
sporophytic generation. The mature micro- 
spore-mother-cell is the first stage in the develop- 
ment of the male gametophyte {cf. 6 {a), 
below, p. 203). 

{h) Around the mother-cells note a layer of elon- 
gate cells, radially arranged, and with nuclei 
more or less disorganized. These are the 
tapetal-cells. Together they form thetapetum. 

{i) Between the tapetum and epidermis lie the 
middle layers of cells forming the wall of the 
sporangium. How many cells thick is it? 

{k) Make a drawing 8 cm. in longest measure, 
showing all features observed under 4, (a)-(k). 

(/) By two successive divisions each pollen-mother- 



202 MORPHOLOGY AND LIFE HISTORY 

cell . forms four microspores (young pollen- 
grains) . They thus arise in tetrads. 
Using slides showing pollen-grains, observe: 

(m) The more advanced disorganization of the 
tapetal-cells, including the breaking down of 
their cell-walls, and the fragmentation of their 
7iuclei into two or more. These cells serve 
to nourish the spore-mother-cells. 

(n) The microspores. Do they lie free or con- 
nected? Describe their shape, surface-features, 
and number of nuclei. 

(o) State again the first stage in the germination 
of the microspore. What is the resulting 
structure? What is its homology? 
5. Megasporangia; megas pore-mother-cell. 

Using prepared slides showing the megaspore- 

mother-cell, observe: 

{a) The outline of the ovary as seen in cross-section. 

Q)) The presence or absence of an epidermis; 
of stomata. 

{c) The cells" of the ovary, each containing, in 
the section, 

{d) Two young ovules (megasporangia). Are the 
ovules straight or curved ? 
At this stage the tissue of the ovule is chiefly 
nuc^llus, but soon there develops at the base 
of the ovule, outside of the nucellus, 

{e) The imier integument, which grows up around 
the nucellus, leaving at the summit only . a 
small passage, 

(/) The micropyle. Outside the inner integument 
there usually develops 

{g) An outer integimient. In anatropous ovules 
the development of the outer integument 



TRILLIUM 203 

wholly or partially fails on the side where the 
funiculus adheres to the ovule. At the summit 
of the nucellus (apex of the ovule) is seen the 
large 

(h) megaspore-mother-cell (embryo-sac-mother- 
cell), with very prominent nucleus and 
nucleolus. 

{i) Make a diagram of all that you have observed 
under 5, {a)-(h), filling in the details for one 
ovule. 

6. Development of the Megaspores. 

(a) Like the microspore-mother-cell, the megaspore- 
mother-cell of Trillium divides twice, giving 
rise to four megaspores (tetrads), but only 
one of these megaspores develops a gametophyte. 
This spore enlarges, and by three successive 
divisions gives rise to an eight-nucleate female 
gametophyte, the embryo-sac. Three of these 
nuclei organize antipodal cells at the basal 
end of the embryo-sac, and three of them 
organize cells at the micropylar end. One of 
the latter is the egg^ the other two the synergids. 
The two remaining nuclei fuse near the center 
of the embryo-sac, forming the endosperm- 
nucleus (sometimes called definitive nucleus), 
but the endosperm does not develop until 
after the fertilization of the egg. 

{h) Unlike the microspores, the megaspores, in 
angiosperms, never become free, independent 
cells, but always retain an intimate physiolog- 
ical connection with the sporophyte of the 
next preceding generation {cf. ^{g), above). 

7. The Embryo-sac. 

(a) Using prepared slides, study the embryo-sac 



204 MORPHOLOGY AND LIFE HISTORY 

in its two- to eight-celled stages,, identif^-mg 
the cells mentioned in 6 above. Draw. 
K, Development of tJie Embryo: 

I. After fertilization (K, 2, (c), p. 199), the oosperm 
develops the embr^'o-sporophyte, and while this 
process is taking place, the endosperm-nucleus, in 
many cases, fuses with the second sperm-cell double 
fertilization). By successive divisions the endo- 
sperm-nucleus develops into endosperm, which sur- 
roimds the embryo and will ser^-e to nourish it when 
it re-awakens, at the *'' germination" of the seed. 
L. Fruit and Seed'. 

1. Meanwhile, as a result of fertilization, the ovary 
resumes growth, and develops into a fruit ripened 
ovar}^) , while the . ovule enlarges and undergoes 
numerous changes, ripening into a seed. 

2. In a concisely worded paragraph. teU what a seed 
is, stating to which of the alternating generations 
the seed-coats, endosperm, and embr3-o belong. 

M. Nutrition: 

I. Discuss the nutrition of both the gametophyte 
and sporophyte of Trillium, as suggested above 
(Z, 1-4, p. 175) for Zamia, 

N. Tabular Review: 

FiU in the tables below (pp. 205 and 206), by placing 
an X in the proper space, then state, in a well- 
worded paragraph for each table, what my be 
learned by an inspection of it. 



TRILLIUM 



205 



Table Ill- 


-Comparison op 


Gametophytes 






Plant 


to 

V 

u 

'ft 

M 

V 

Pi 


m 
a> 

.*" 

*M 

a 
>. 

CO 




e 


M 

ca 


g 
1 

C/3 

■•J 

01 (_ 


1 

OJ 

bo 
.c 
'•+3 
u 

c 


"3 


Can exist independ- 
ently of the sporo- 
phyte 



.Ho 

Co 

ft IH 



>i 10 

^^ 


c 





CO 

3 

'S 
8 
c 



M 

3 
.0 
'0 

8 

s 


X 

CO 

C9 

0.2 
*^ 
C8 

<3- 


Has both vegetative 
and reproductive 
functions 


CO 

a 



c 

3 

S 

1- 


Riccia 

Anthoceros 

Sphagnum 

Polypodium 

Equisetum 

Lycopodium 

Selaginella 

Isoetes 


I 


2 


3 


4 


5 


6 


7 


8 


9 


10 


II 


12 


13 


Zamia 


























. . . 


Pinus 




























Trillium 





























2o6 



MORPHOLOGY AND LIFE HISTORY 



Seeds inclosed in an 

ovary- 


























Seeds not inclosed in 
an ovary 


00 
























Produces seeds 


t^ 
























Produces no seeds 


























Heterosporous 


>0 
























Homosporous 


M 
























Vegetative functions 
predominate 


























Reproductive func- 
tions predominate 


M 
























Capable of asexual 
propagation 


W 
M 
























Wholly parasitic on 
gametophyte 


O 
























Partly parasitic on 
gametophyte 


Oi 
























Can exist independent 
of gametophyte 


00 
























Has conducting tissue 


r^ 
























Takes nourishment 
from the soil 


o 
























Has stomata 


lO 
























Has chlorophyll 


•* 
























Respires 


n 
























Passes through an em- 
bryonic to a more 
highly developed stage 
of maturity 


N 
























Never passes beyond 
an essentially embry- 
onic stage 


M 


























'Z 
c. 


c 

4 

C. 

1 c 

^ < 


1 c 

: c 


\ i 


I i 

X a 


c 

1 c 

I J 

5 ►- 


n 

^ 1 

^ "a 

5 </ 


1/ 




i t/ 

i 1 


1 E 


4 



^>^,,'?imR-^^W-B'm^u:^'^^^ 



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